Looking for the best practice material for Class 10 Science Assertion and Reasoning Questions? You’re at the right place! Here we provide 102 Assertion and Reasoning MCQs from Physics, Chemistry, and Biology – all in quiz format with detailed answers.
These Assertion and Reason Questions for Class 10 Science are based on the latest CBSE exam pattern 2025, helping you strengthen conceptual clarity and prepare effectively for board exams.
Why Practice Assertion and Reason Questions?
Assertion and Reasoning type questions are often considered tricky in CBSE Class 10 Science. Practicing them will help you:
- Improve logical reasoning and concept clarity.
- Score better in MCQ-based sections of the paper.
- Build exam confidence by solving real board exam style questions.
Assertion–reason MCQs
Q1. Assertion (A): The surface of copper powder becomes black on heating.
Reason (R): Black colour copper oxide is formed.
Reason (R): Black colour copper oxide is formed.
Correct Answer: A
When copper powder is heated, it reacts with oxygen to form copper(II) oxide, which is black. The reason correctly explains the assertion.
When copper powder is heated, it reacts with oxygen to form copper(II) oxide, which is black. The reason correctly explains the assertion.
Q2. Assertion (A): Concave mirrors are used as make-up mirrors.
Reason (R): When the face is held within the focus of a concave mirror, then a diminished image of the face is seen in the concave mirror.
Reason (R): When the face is held within the focus of a concave mirror, then a diminished image of the face is seen in the concave mirror.
Correct Answer: C
Assertion is true. Concave mirrors are used as make-up mirrors because they produce a magnified and erect image when the object is placed between the pole and the focus. The reason is false as it states a diminished image is formed.
Assertion is true. Concave mirrors are used as make-up mirrors because they produce a magnified and erect image when the object is placed between the pole and the focus. The reason is false as it states a diminished image is formed.
Q3. Assertion (A): The stars twinkle, while the planets do not.
Reason (R): The stars are much bigger in size than the planets.
Reason (R): The stars are much bigger in size than the planets.
Correct Answer: B
Both statements are true. Stars twinkle due to atmospheric refraction of starlight. Planets, being closer, are seen as extended sources, and the twinkling effect averages out. While stars are much bigger than planets, this is not the reason for their twinkling.
Both statements are true. Stars twinkle due to atmospheric refraction of starlight. Planets, being closer, are seen as extended sources, and the twinkling effect averages out. While stars are much bigger than planets, this is not the reason for their twinkling.
Q4. Assertion (A): Brown fumes are obtained from the thermal decomposition of Lead Nitrate.
Reason (R): Nitrogen dioxide gas is released which is brown in colour.
Reason (R): Nitrogen dioxide gas is released which is brown in colour.
Correct Answer: A
The thermal decomposition of lead nitrate produces lead oxide, oxygen, and nitrogen dioxide gas. Nitrogen dioxide gas is brown in colour, hence the brown fumes.
The thermal decomposition of lead nitrate produces lead oxide, oxygen, and nitrogen dioxide gas. Nitrogen dioxide gas is brown in colour, hence the brown fumes.
Q5. Assertion (A): Just before sunset, the sun appears to be elliptical. this may happen due to refraction.
Reason (R): Refraction of light rays through atmosphere may cause different magnification in mutually perpendicular directions.
Reason (R): Refraction of light rays through atmosphere may cause different magnification in mutually perpendicular directions.
Correct Answer: A
Atmospheric refraction causes the apparent flattening or elliptical shape of the sun at sunrise and sunset because light from the lower edge is refracted more than light from the upper edge. The reason correctly explains this phenomenon.
Atmospheric refraction causes the apparent flattening or elliptical shape of the sun at sunrise and sunset because light from the lower edge is refracted more than light from the upper edge. The reason correctly explains this phenomenon.
Q6. Assertion (A): The property of beating a metal into sheets is called ductility.
Reason (R): Gold and silver are most malleable metals.
Reason (R): Gold and silver are most malleable metals.
Correct Answer: D
Assertion is false; the property of beating a metal into sheets is called malleability, not ductility. Ductility is the ability to be drawn into wires. The reason is true; gold and silver are the most malleable metals.
Assertion is false; the property of beating a metal into sheets is called malleability, not ductility. Ductility is the ability to be drawn into wires. The reason is true; gold and silver are the most malleable metals.
Q7. Assertion (A): At high altitudes the pressure of oxygen falls, inside lungs.
Reason (R): Oxygen is absorbed very quickly from alveoli to increase breathing.
Reason (R): Oxygen is absorbed very quickly from alveoli to increase breathing.
Correct Answer: C
The assertion is true; at high altitudes, the partial pressure of oxygen is lower, leading to lower oxygen pressure in the lungs. The reason is false; the rate of oxygen absorption slows down due to the lower pressure gradient.
The assertion is true; at high altitudes, the partial pressure of oxygen is lower, leading to lower oxygen pressure in the lungs. The reason is false; the rate of oxygen absorption slows down due to the lower pressure gradient.
Q8. Assertion (A): For observing traffic at back, the driver mirror is convex mirror.
Reason (R): A convex mirror has much larger field of view than a plane mirror.
Reason (R): A convex mirror has much larger field of view than a plane mirror.
Correct Answer: A
Convex mirrors are used as rear-view mirrors in vehicles because they provide a wider field of view, allowing the driver to see more of the area behind them. The reason correctly explains the assertion.
Convex mirrors are used as rear-view mirrors in vehicles because they provide a wider field of view, allowing the driver to see more of the area behind them. The reason correctly explains the assertion.
Q9. Assertion (A): On reacting with water, calcium starts floating over water.
Reason (R): Calcium reacts with cold water at room temperature.
Reason (R): Calcium reacts with cold water at room temperature.
Correct Answer: B
Both statements are true. Calcium floats because the bubbles of hydrogen gas produced during the reaction stick to its surface. While it does react with cold water, this fact alone doesn’t explain why it floats.
Both statements are true. Calcium floats because the bubbles of hydrogen gas produced during the reaction stick to its surface. While it does react with cold water, this fact alone doesn’t explain why it floats.
Q10. Assertion (A): kidneys perform a dual function in our body.
Reason (R): selective reabsorption occurs in the glomerulus.
Reason (R): selective reabsorption occurs in the glomerulus.
Correct Answer: C
Assertion is true; kidneys perform filtration (excretion) and osmoregulation. Reason is false; selective reabsorption occurs in the renal tubules, not the glomerulus, where ultrafiltration takes place.
Assertion is true; kidneys perform filtration (excretion) and osmoregulation. Reason is false; selective reabsorption occurs in the renal tubules, not the glomerulus, where ultrafiltration takes place.
Q11. Assertion (A): Iron nails turn blue colour copper sulphate solution to green colour.
Reason (R): Copper is more reactive than iron.
Reason (R): Copper is more reactive than iron.
Correct Answer: C
Assertion is true. This happens because iron displaces copper from the copper sulphate solution, forming iron sulphate, which is green. The reason is false; iron is more reactive than copper, which is why it can displace it.
Assertion is true. This happens because iron displaces copper from the copper sulphate solution, forming iron sulphate, which is green. The reason is false; iron is more reactive than copper, which is why it can displace it.
Q12. Assertion (A): Veins have valves.
Reason (R): the pressure for the flow is far lesser compared to arteries.
Reason (R): the pressure for the flow is far lesser compared to arteries.
Correct Answer: A
Veins have valves to prevent the backflow of blood, especially in the limbs. This is necessary because the blood in veins is at a much lower pressure than in arteries, and valves help ensure it continues to flow towards the heart.
Veins have valves to prevent the backflow of blood, especially in the limbs. This is necessary because the blood in veins is at a much lower pressure than in arteries, and valves help ensure it continues to flow towards the heart.
Q13. Assertion (A): The acid must always be added to water with constant stirring.
Reason (R): Mixing of an acid with water decreases the conc. of H+ ions per unit volume.
Reason (R): Mixing of an acid with water decreases the conc. of H+ ions per unit volume.
Correct Answer: B
Both statements are true. Acid should be added to water because the dilution process is highly exothermic. While dilution does decrease the concentration of H+ ions, the primary safety reason for adding acid to water is to dissipate the heat generated and prevent splashing.
Both statements are true. Acid should be added to water because the dilution process is highly exothermic. While dilution does decrease the concentration of H+ ions, the primary safety reason for adding acid to water is to dissipate the heat generated and prevent splashing.
Q14. Assertion (A): The Alveoli provide a surface where exchange of gases takes place.
Reason (R): The Alveolar blood vessels transport oxygenated blood to all the cells of the body.
Reason (R): The Alveolar blood vessels transport oxygenated blood to all the cells of the body.
Correct Answer: C
Assertion is true. Reason is false; alveolar blood vessels (pulmonary veins) transport oxygenated blood from the lungs to the heart, which then pumps it to the rest of the body.
Assertion is true. Reason is false; alveolar blood vessels (pulmonary veins) transport oxygenated blood from the lungs to the heart, which then pumps it to the rest of the body.
Q15. Assertion (A): Silver and gold do not react with oxygen even at high temperatures.
Reason (R): Silver and gold are less active metals.
Reason (R): Silver and gold are less active metals.
Correct Answer: A
Silver and gold are noble metals, meaning they are very unreactive. Their low activity is the reason they do not react with oxygen, even at high temperatures.
Silver and gold are noble metals, meaning they are very unreactive. Their low activity is the reason they do not react with oxygen, even at high temperatures.
Q16. Assertion (A): Honey bee-sting injects an acid in the skin which causes pain and irritation.
Reason (R): Use of mild base like baking soda on the stung area gives relief.
Reason (R): Use of mild base like baking soda on the stung area gives relief.
Correct Answer: B
Both statements are true. A bee sting is acidic, and applying a mild base like baking soda neutralizes the acid, providing relief. However, the reason doesn’t explain the assertion; it describes the remedy.
Both statements are true. A bee sting is acidic, and applying a mild base like baking soda neutralizes the acid, providing relief. However, the reason doesn’t explain the assertion; it describes the remedy.
Q17. Assertion (A): In case of rainbow, light at the inner surface of the water drop gets internally
reflected.
Reason (R): The angle between the refracted ray and normal to the drop surface is greater than the critical angle.
Reason (R): The angle between the refracted ray and normal to the drop surface is greater than the critical angle.
Correct Answer: A
For a rainbow to form, sunlight undergoes total internal reflection inside water droplets. This occurs when the angle of incidence at the water-air boundary is greater than the critical angle.
For a rainbow to form, sunlight undergoes total internal reflection inside water droplets. This occurs when the angle of incidence at the water-air boundary is greater than the critical angle.
Q18. Assertion (A): Lypase helps in the digestion of proteins.
Reason (R): Digestion of proteins in small intestine needs basic medium.
Reason (R): Digestion of proteins in small intestine needs basic medium.
Correct Answer: D
Assertion is false; lipase helps in the digestion of fats (lipids), not proteins. Proteases like trypsin digest proteins. Reason is true; enzymes like trypsin work optimally in the alkaline (basic) medium of the small intestine.
Assertion is false; lipase helps in the digestion of fats (lipids), not proteins. Proteases like trypsin digest proteins. Reason is true; enzymes like trypsin work optimally in the alkaline (basic) medium of the small intestine.
Q19. Assertion (A): It is impossible to see virtual image with our naked Eye.
Reason (R): The rays do not actually emanate from a virtual image.
Reason (R): The rays do not actually emanate from a virtual image.
Correct Answer: D
Assertion is false; we see virtual images all the time, for example, our reflection in a plane mirror. Reason is true; a virtual image is formed where rays appear to diverge from, but they do not actually meet there.
Assertion is false; we see virtual images all the time, for example, our reflection in a plane mirror. Reason is true; a virtual image is formed where rays appear to diverge from, but they do not actually meet there.
Q20. Assertion (A): The chemical formula of bleaching powder is CaOCl2.
Reason (R): Chlorine gas is passed over Calcium Oxide to form bleaching powder.
Reason (R): Chlorine gas is passed over Calcium Oxide to form bleaching powder.
Correct Answer: C
Assertion is true. The reason is false; bleaching powder is formed by passing chlorine gas over slaked lime (Calcium Hydroxide, Ca(OH)2), not Calcium Oxide (CaO).
Assertion is true. The reason is false; bleaching powder is formed by passing chlorine gas over slaked lime (Calcium Hydroxide, Ca(OH)2), not Calcium Oxide (CaO).
Q21. Assertion (A): In plants gaseous exchange takes place by the opening and closing of guard cells.
Reason (R): The exchange of gases occurs across the surface of stem, roots and leaves.
Reason (R): The exchange of gases occurs across the surface of stem, roots and leaves.
Correct Answer: B
Both are true. Gaseous exchange in leaves is controlled by stomata (guard cells). However, gaseous exchange also happens through lenticels in stems and the surface of roots. So, the reason is a broader true statement but not the direct explanation for the specific mechanism in leaves.
Both are true. Gaseous exchange in leaves is controlled by stomata (guard cells). However, gaseous exchange also happens through lenticels in stems and the surface of roots. So, the reason is a broader true statement but not the direct explanation for the specific mechanism in leaves.
Q22. Assertion (A): The colour of the scattered light does not depend on the size of the scattering
particles.
Reason (R): Red light is used as a danger signal because it can travel longer distances through rain and fog.
Reason (R): Red light is used as a danger signal because it can travel longer distances through rain and fog.
Correct Answer: D
Assertion is false; the colour of scattered light highly depends on the particle size (e.g., Rayleigh vs. Mie scattering). Reason is true; red light has the longest wavelength and is scattered the least, allowing it to be seen from a distance.
Assertion is false; the colour of scattered light highly depends on the particle size (e.g., Rayleigh vs. Mie scattering). Reason is true; red light has the longest wavelength and is scattered the least, allowing it to be seen from a distance.
Q23. Assertion (A): The emergent ray is parallel to the direction of incident ray.
Reason (R): The extent of bending of the ray of light at the opposite parallel faces (air- glass interface and glass- air interface) of the rectangular glass slab is equal and opposite.
Reason (R): The extent of bending of the ray of light at the opposite parallel faces (air- glass interface and glass- air interface) of the rectangular glass slab is equal and opposite.
Correct Answer: A
When light passes through a rectangular glass slab, the emergent ray is parallel to the incident ray (though laterally displaced). This is because the refraction at the first surface is equal and opposite to the refraction at the second surface.
When light passes through a rectangular glass slab, the emergent ray is parallel to the incident ray (though laterally displaced). This is because the refraction at the first surface is equal and opposite to the refraction at the second surface.
Q24. Assertion (A): During transpiration the evaporating water carries away heat energy.
Reason (R): Due to water loss the osmotic pressure inside leaves increases.
Reason (R): Due to water loss the osmotic pressure inside leaves increases.
Correct Answer: C
Assertion is true; transpiration has a cooling effect on the plant. Reason is false; as water is lost, the concentration of solutes inside the leaf cells increases, which in turn increases the osmotic pressure, helping to draw more water up from the roots. The PDF answer key states C, implying the reason is considered false in this context, likely focusing on the assertion not being a direct result of osmotic pressure change.
Assertion is true; transpiration has a cooling effect on the plant. Reason is false; as water is lost, the concentration of solutes inside the leaf cells increases, which in turn increases the osmotic pressure, helping to draw more water up from the roots. The PDF answer key states C, implying the reason is considered false in this context, likely focusing on the assertion not being a direct result of osmotic pressure change.
Q25. Assertion (A): Addition of oxygen is oxidation.
Reason (R): Removal of oxygen is reduction.
Reason (R): Removal of oxygen is reduction.
Correct Answer: B
Both statements are the definitions of oxidation and reduction in terms of oxygen. They are both true but are separate definitions; one does not explain the other.
Both statements are the definitions of oxidation and reduction in terms of oxygen. They are both true but are separate definitions; one does not explain the other.
Q26. Assertion (A): At Mid-day sun appears to be bright white.
Reason (R): Scattering occurs due to size of dust particles and Air molecules.
Reason (R): Scattering occurs due to size of dust particles and Air molecules.
Correct Answer: A
At midday, the sun is directly overhead, and sunlight travels the shortest distance through the atmosphere. This results in minimal scattering of light by air molecules, so most colours reach our eyes, making the sun appear white.
At midday, the sun is directly overhead, and sunlight travels the shortest distance through the atmosphere. This results in minimal scattering of light by air molecules, so most colours reach our eyes, making the sun appear white.
Q27. Assertion (A): Higher the Refractive index of the medium lesser will be the speed of light in that
Medium.
Reason (R): Refractive index is inversely proportional to the speed of light.
Reason (R): Refractive index is inversely proportional to the speed of light.
Correct Answer: A
The refractive index (n) of a medium is defined as the ratio of the speed of light in a vacuum (c) to the speed of light in that medium (v), i.e., n = c/v. This relationship is an inverse proportion, so the reason correctly explains the assertion.
The refractive index (n) of a medium is defined as the ratio of the speed of light in a vacuum (c) to the speed of light in that medium (v), i.e., n = c/v. This relationship is an inverse proportion, so the reason correctly explains the assertion.
Q28. Assertion (A): The twinkling of stars is due to the fact that refractive index of the earth’s
atmosphere fluctuates.
Reason (R): In cold countries, the phenomenon of looming (i.e ship appears in the sky) takes place, because refractive index of air decreases with height.
Reason (R): In cold countries, the phenomenon of looming (i.e ship appears in the sky) takes place, because refractive index of air decreases with height.
Correct Answer: B
Both are true statements related to atmospheric refraction. The twinkling of stars is caused by the continuous change in the refractive index of atmospheric layers. Looming is another phenomenon caused by atmospheric refraction under specific temperature conditions. However, looming doesn’t explain twinkling.
Both are true statements related to atmospheric refraction. The twinkling of stars is caused by the continuous change in the refractive index of atmospheric layers. Looming is another phenomenon caused by atmospheric refraction under specific temperature conditions. However, looming doesn’t explain twinkling.
Q29. Assertion (A): Hydrogen gas is not evolved when a metal reacts with nitric acid.
Reason (R): Nitric acid is a strong oxidising agent.
Reason (R): Nitric acid is a strong oxidising agent.
Correct Answer: A
Nitric acid is a strong oxidizing agent. When it reacts with metals, it oxidizes the hydrogen gas produced to water, and itself gets reduced to nitrogen oxides. Thus, H2 gas is not evolved. (Exceptions: very dilute HNO3 with Mg or Mn).
Nitric acid is a strong oxidizing agent. When it reacts with metals, it oxidizes the hydrogen gas produced to water, and itself gets reduced to nitrogen oxides. Thus, H2 gas is not evolved. (Exceptions: very dilute HNO3 with Mg or Mn).
Q30. Assertion (A): Electrovalency of Na is +1.
Reason (R): The number of electrons which an atom either loses or gains in the formation of an ionic bond is known as its valency.
Reason (R): The number of electrons which an atom either loses or gains in the formation of an ionic bond is known as its valency.
Correct Answer: B
Assertion is true; Sodium (Na) loses one electron to achieve a stable configuration, giving it an electrovalency of +1. The reason provides a general definition of valency/electrovalency, which is also true, but it doesn’t specifically explain why Na’s is +1.
Assertion is true; Sodium (Na) loses one electron to achieve a stable configuration, giving it an electrovalency of +1. The reason provides a general definition of valency/electrovalency, which is also true, but it doesn’t specifically explain why Na’s is +1.
Q31. Assertion (A): Bread tastes sweet on mastication.
Reason (R): Salivary amylase converts starch into sugar.
Reason (R): Salivary amylase converts starch into sugar.
Correct Answer: A
Bread is rich in starch. When it is chewed (masticated), the salivary amylase in saliva begins breaking down the complex starch into simpler sugars (like maltose), which taste sweet.
Bread is rich in starch. When it is chewed (masticated), the salivary amylase in saliva begins breaking down the complex starch into simpler sugars (like maltose), which taste sweet.
Q32. Assertion (A): Reaction between Barium Hydroxide and Ammonium Chloride makes the test tube cool to
touch.
Reason (R): It is an example of endothermic reaction.
Reason (R): It is an example of endothermic reaction.
Correct Answer: A
The reaction is endothermic, meaning it absorbs heat from the surroundings. This absorption of heat causes the temperature of the test tube to drop, making it feel cool.
The reaction is endothermic, meaning it absorbs heat from the surroundings. This absorption of heat causes the temperature of the test tube to drop, making it feel cool.
Q33. Assertion (A): NaHCO3 + HCl = NaCl + H2O + CO2
Reason (R): Evolved gas catches fire immediately.
Reason (R): Evolved gas catches fire immediately.
Correct Answer: C
Assertion is true; it is a correct chemical equation for the reaction of sodium bicarbonate with hydrochloric acid. The reason is false; the gas evolved is Carbon Dioxide (CO2), which extinguishes fire, it does not catch fire.
Assertion is true; it is a correct chemical equation for the reaction of sodium bicarbonate with hydrochloric acid. The reason is false; the gas evolved is Carbon Dioxide (CO2), which extinguishes fire, it does not catch fire.
Q34. Assertion (A): The colour of salts does not depend on water of crystallisation.
Reason (R): Ferrous Sulphate crystals are blue in colour because of the seven water molecules of crystallisation.
Reason (R): Ferrous Sulphate crystals are blue in colour because of the seven water molecules of crystallisation.
Correct Answer: D
Assertion is false. The colour of many salts, like copper sulphate and ferrous sulphate, is due to the presence of water of crystallisation. The reason is also false; hydrated ferrous sulphate (FeSO4·7H2O) is green, not blue. Hydrated copper sulphate is blue.
Assertion is false. The colour of many salts, like copper sulphate and ferrous sulphate, is due to the presence of water of crystallisation. The reason is also false; hydrated ferrous sulphate (FeSO4·7H2O) is green, not blue. Hydrated copper sulphate is blue.
Q35. Assertion (A): Anaerobic respiration requires more energy as compared to aerobic respiration.
Reason (R): Mitochondria is the power house of the cell.
Reason (R): Mitochondria is the power house of the cell.
Correct Answer: D
Assertion is false; anaerobic respiration produces far less energy (approx. 2 ATP) than aerobic respiration (approx. 38 ATP). Reason is true; mitochondria are where the main energy-releasing steps of aerobic respiration occur.
Assertion is false; anaerobic respiration produces far less energy (approx. 2 ATP) than aerobic respiration (approx. 38 ATP). Reason is true; mitochondria are where the main energy-releasing steps of aerobic respiration occur.
Q36. Assertion (A): The number of atoms of each element remains the same, before and after a chemical
reaction.
Reason (R): Any chemical equation can be unbalanced because the mass may not be same on both sides of the equation.
Reason (R): Any chemical equation can be unbalanced because the mass may not be same on both sides of the equation.
Correct Answer: C
The assertion is a statement of the Law of Conservation of Mass, which is true. The reason is false; a correct chemical equation must be balanced, ensuring the mass is the same on both sides.
The assertion is a statement of the Law of Conservation of Mass, which is true. The reason is false; a correct chemical equation must be balanced, ensuring the mass is the same on both sides.
Q37. Assertion (A): Light travels faster in water than air.
Reason (R): Water is denser than Air.
Reason (R): Water is denser than Air.
Correct Answer: D
Assertion is false; light travels slower in optically denser mediums. Since water is optically denser than air, light travels slower in water. The reason is true; water is optically denser than air.
Assertion is false; light travels slower in optically denser mediums. Since water is optically denser than air, light travels slower in water. The reason is true; water is optically denser than air.
Q38. Assertion (A): The angle of incidence for a ray of light having zero angle of reflection is two.
Reason (R): Refracting surfaces follow Snell’s Law.
Reason (R): Refracting surfaces follow Snell’s Law.
Correct Answer: D
Assertion is false. According to the laws of reflection, the angle of incidence is always equal to the angle of reflection. If the angle of reflection is zero, the angle of incidence must also be zero. The reason is true, but it relates to refraction, not reflection.
Assertion is false. According to the laws of reflection, the angle of incidence is always equal to the angle of reflection. If the angle of reflection is zero, the angle of incidence must also be zero. The reason is true, but it relates to refraction, not reflection.
Q39. Assertion (A): The Sun appears flattened at sunrise and sunset.
Reason (R): The apparent flattering of the Sun’s disc at sunrise and sunset is due to atmospheric refraction.
Reason (R): The apparent flattering of the Sun’s disc at sunrise and sunset is due to atmospheric refraction.
Correct Answer: A
The sun does appear flattened (oval) at sunrise and sunset. This is an optical phenomenon caused by the refraction of sunlight as it passes through the Earth’s atmosphere.
The sun does appear flattened (oval) at sunrise and sunset. This is an optical phenomenon caused by the refraction of sunlight as it passes through the Earth’s atmosphere.
Q40. Assertion (A): Silver Chloride turns grey in sunlight.
Reason (R): This is an example of thermal decomposition.
Reason (R): This is an example of thermal decomposition.
Correct Answer: C
Assertion is true; silver chloride decomposes into silver (grey) and chlorine gas. The reason is false; this decomposition is caused by light, so it is a photochemical decomposition, not thermal (heat) decomposition.
Assertion is true; silver chloride decomposes into silver (grey) and chlorine gas. The reason is false; this decomposition is caused by light, so it is a photochemical decomposition, not thermal (heat) decomposition.
Q41. Assertion (A): The mirrors used in search lights are concave spherical.
Reason (R): In concave spherical mirror the image formed is always virtual.
Reason (R): In concave spherical mirror the image formed is always virtual.
Correct Answer: C
Assertion is true; concave mirrors are used in searchlights to produce a powerful, parallel beam of light when the source is placed at the focus. The reason is false; concave mirrors can form both real and virtual images depending on the object’s position.
Assertion is true; concave mirrors are used in searchlights to produce a powerful, parallel beam of light when the source is placed at the focus. The reason is false; concave mirrors can form both real and virtual images depending on the object’s position.
Q42. Assertion (A): MgCl2 is a covalent compound.
Reason (R): MgCl2 is a good conductor of electricity in molten state.
Reason (R): MgCl2 is a good conductor of electricity in molten state.
Correct Answer: D
Assertion is false; MgCl2 is an ionic compound formed by the transfer of electrons from magnesium to chlorine. Reason is true; ionic compounds conduct electricity in their molten state because the ions are free to move.
Assertion is false; MgCl2 is an ionic compound formed by the transfer of electrons from magnesium to chlorine. Reason is true; ionic compounds conduct electricity in their molten state because the ions are free to move.
Q43. Assertion (A): The sky appears dark in outer space.
Reason (R): Scattering does not occur in outer space as there is no atmosphere.
Reason (R): Scattering does not occur in outer space as there is no atmosphere.
Correct Answer: A
The blue colour of the sky on Earth is due to the scattering of sunlight by atmospheric particles. In the vacuum of outer space, there is no atmosphere to scatter the light, so the sky appears black or dark.
The blue colour of the sky on Earth is due to the scattering of sunlight by atmospheric particles. In the vacuum of outer space, there is no atmosphere to scatter the light, so the sky appears black or dark.
Q44. Assertion (A): Zinc oxide is amphoteric in nature.
Reason (R): Zinc oxide reacts with both acids and bases.
Reason (R): Zinc oxide reacts with both acids and bases.
Correct Answer: A
Amphoteric substances are those that can react with both acids and bases. Zinc oxide exhibits this property, making it amphoteric. The reason correctly defines the assertion.
Amphoteric substances are those that can react with both acids and bases. Zinc oxide exhibits this property, making it amphoteric. The reason correctly defines the assertion.
Q45. Assertion (A): The formula connecting u, v and f for a spherical mirror is valid in all situations for
all spherical mirrors for all positions of the object.
Reason (R): Laws of reflection are strictly valid for plane surfaces.
Reason (R): Laws of reflection are strictly valid for plane surfaces.
Correct Answer: C
Assertion is true; the mirror formula (1/v + 1/u = 1/f) is generally applicable for all spherical mirrors under the paraxial approximation. The reason is false; the laws of reflection are valid for all reflecting surfaces, including curved ones.
Assertion is true; the mirror formula (1/v + 1/u = 1/f) is generally applicable for all spherical mirrors under the paraxial approximation. The reason is false; the laws of reflection are valid for all reflecting surfaces, including curved ones.
Q46. Assertion (A): When the object moves with a velocity 2 m/s, its image in the plane mirror moves with a
velocity of 4 m/s.
Reason (R): The image formed by a plane mirror is as far behind the mirror as the object is in front of it.
Reason (R): The image formed by a plane mirror is as far behind the mirror as the object is in front of it.
Correct Answer: D
Assertion is false. The speed of the image relative to the mirror is the same as the speed of the object relative to the mirror (2 m/s). The speed of the image relative to the object is 4 m/s. The assertion is ambiguously worded but typically refers to the speed of the image itself, not relative to the object. Reason is a true property of plane mirrors. The PDF answer key states A, which implies the question interprets “moves with a velocity of 4 m/s” as the relative velocity between object and image.
Assertion is false. The speed of the image relative to the mirror is the same as the speed of the object relative to the mirror (2 m/s). The speed of the image relative to the object is 4 m/s. The assertion is ambiguously worded but typically refers to the speed of the image itself, not relative to the object. Reason is a true property of plane mirrors. The PDF answer key states A, which implies the question interprets “moves with a velocity of 4 m/s” as the relative velocity between object and image.
Q47. Assertion (A): The HCl gas shows acidic behaviour in the water.
Reason (R): The pH of dry HCl gas is 1.5.
Reason (R): The pH of dry HCl gas is 1.5.
Correct Answer: C
Assertion is true; HCl dissociates into H+ and Cl- ions in water, which is responsible for its acidic properties. The reason is false; dry HCl gas does not produce H+ ions, so it is not acidic and does not have a pH value. The concept of pH applies to aqueous solutions.
Assertion is true; HCl dissociates into H+ and Cl- ions in water, which is responsible for its acidic properties. The reason is false; dry HCl gas does not produce H+ ions, so it is not acidic and does not have a pH value. The concept of pH applies to aqueous solutions.
Q48. Assertion (A): A prism can split the incident white light into bands of different colours.
Reason (R): The different colours of light bend through different angles with respect to the incident rays.
Reason (R): The different colours of light bend through different angles with respect to the incident rays.
Correct Answer: A
The phenomenon of splitting white light into its constituent colours is called dispersion. It occurs because the refractive index of the prism material is different for different wavelengths (colours) of light, causing each colour to bend at a slightly different angle.
The phenomenon of splitting white light into its constituent colours is called dispersion. It occurs because the refractive index of the prism material is different for different wavelengths (colours) of light, causing each colour to bend at a slightly different angle.
Q49. Assertion (A): The path of light is visible due to scattering of light.
Reason (R): Tiny water droplets in the mist scatter light.
Reason (R): Tiny water droplets in the mist scatter light.
Correct Answer: B
Both are true statements. The Tyndall effect makes a light path visible when scattered by particles. Mist scattering light is an example of this. However, the reason is just one specific example, not the general explanation for the assertion.
Both are true statements. The Tyndall effect makes a light path visible when scattered by particles. Mist scattering light is an example of this. However, the reason is just one specific example, not the general explanation for the assertion.
Q50. Assertion (A): The oxides of sulphur and phosphorus are acidic in nature.
Reason (R): Metal oxides are basic in nature.
Reason (R): Metal oxides are basic in nature.
Correct Answer: B
Assertion is true; oxides of non-metals like sulphur and phosphorus are acidic. Reason is also a true general statement (with exceptions like amphoteric oxides). However, the reason about metal oxides does not explain why non-metal oxides are acidic.
Assertion is true; oxides of non-metals like sulphur and phosphorus are acidic. Reason is also a true general statement (with exceptions like amphoteric oxides). However, the reason about metal oxides does not explain why non-metal oxides are acidic.
Q51. Assertion (A): Herbivores have longer intestine to allow the cellulose to get digested.
Reason (R): Carnivores have shorter intestine to allow meat to get digested.
Reason (R): Carnivores have shorter intestine to allow meat to get digested.
Correct Answer: B
Both statements are true facts about the digestive systems of herbivores and carnivores. However, the reason (about carnivores) does not explain the assertion (about herbivores). They are two separate, correct statements.
Both statements are true facts about the digestive systems of herbivores and carnivores. However, the reason (about carnivores) does not explain the assertion (about herbivores). They are two separate, correct statements.
Q52. Assertion (A): The angle of incidence and the angle of emergence are equal.
Reason (R): The angle of refraction and the angle of deviation are not equal.
Reason (R): The angle of refraction and the angle of deviation are not equal.
Correct Answer: B
Both are true statements regarding a light ray passing through a glass prism. However, the inequality of refraction and deviation angles doesn’t explain why the incidence and emergence angles are equal.
Both are true statements regarding a light ray passing through a glass prism. However, the inequality of refraction and deviation angles doesn’t explain why the incidence and emergence angles are equal.
Q53. Assertion (A): Arteries always carry oxygenated blood.
Reason (R): Arteries transport blood from the heart to different parts of the body.
Reason (R): Arteries transport blood from the heart to different parts of the body.
Correct Answer: D
Assertion is false; the pulmonary artery carries deoxygenated blood from the heart to the lungs. Reason is true; the definition of an artery is a vessel that carries blood away from the heart.
Assertion is false; the pulmonary artery carries deoxygenated blood from the heart to the lungs. Reason is true; the definition of an artery is a vessel that carries blood away from the heart.
Q54. Assertion (A): Light changes its speed when it passes from one medium to another.
Reason (R): When a ray travels from vacuum to a medium, then refractive index is known as absolute refractive index.
Reason (R): When a ray travels from vacuum to a medium, then refractive index is known as absolute refractive index.
Correct Answer: B
Both are true statements. Light changes speed due to the change in the optical density of the medium. The reason provides the definition of absolute refractive index, which is a related but separate concept.
Both are true statements. Light changes speed due to the change in the optical density of the medium. The reason provides the definition of absolute refractive index, which is a related but separate concept.
Q55. Assertion (A): The reaction of calcium with water is less violent in comparison to that of sodium.
Reason (R): The heat evolved is not sufficient for the hydrogen to catch fire.
Reason (R): The heat evolved is not sufficient for the hydrogen to catch fire.
Correct Answer: A
The reaction of sodium with water is highly exothermic and violent, igniting the hydrogen gas produced. The reaction of calcium is less exothermic, and the heat produced is not enough to ignite the hydrogen, making it less violent.
The reaction of sodium with water is highly exothermic and violent, igniting the hydrogen gas produced. The reaction of calcium is less exothermic, and the heat produced is not enough to ignite the hydrogen, making it less violent.
Q56. Assertion (A): Plaster of Paris is stored in moisture proof containers.
Reason (R): Plaster of Paris sets into a hard mass on coming in contact with water to form anhydrous Calcium Sulphate.
Reason (R): Plaster of Paris sets into a hard mass on coming in contact with water to form anhydrous Calcium Sulphate.
Correct Answer: C
Assertion is true. The reason is false because when Plaster of Paris reacts with water, it forms gypsum (hydrated Calcium Sulphate, CaSO4·2H2O), not anhydrous Calcium Sulphate.
Assertion is true. The reason is false because when Plaster of Paris reacts with water, it forms gypsum (hydrated Calcium Sulphate, CaSO4·2H2O), not anhydrous Calcium Sulphate.
Q57. Assertion (A): Rainbow is formed in the sky due to the dispersion of sunlight by water droplets.
Reason (R): Light of shorter wavelength is scattered much more than the light of longer wavelength.
Reason (R): Light of shorter wavelength is scattered much more than the light of longer wavelength.
Correct Answer: B
Assertion is true; rainbow formation is a result of dispersion, refraction, and internal reflection of sunlight by water droplets. The reason describes Rayleigh scattering, which explains why the sky is blue, but it does not explain the formation of a rainbow. Both are true but unrelated phenomena.
Assertion is true; rainbow formation is a result of dispersion, refraction, and internal reflection of sunlight by water droplets. The reason describes Rayleigh scattering, which explains why the sky is blue, but it does not explain the formation of a rainbow. Both are true but unrelated phenomena.
Q58. Assertion (A): After white washing the walls, a shiny white finish on walls is obtained after three or
four days.
Reason (R): Calcium hydroxide reacts with Carbon dioxide to form Calcium Carbonate which gives shiny white finish.
Reason (R): Calcium hydroxide reacts with Carbon dioxide to form Calcium Carbonate which gives shiny white finish.
Correct Answer: A
Whitewash contains slaked lime (Calcium Hydroxide). It reacts slowly with CO2 from the air over a few days to form a thin, hard layer of Calcium Carbonate, which provides the shiny finish.
Whitewash contains slaked lime (Calcium Hydroxide). It reacts slowly with CO2 from the air over a few days to form a thin, hard layer of Calcium Carbonate, which provides the shiny finish.
Q59. Assertion (A): The glucose combines with oxygen in the cells of our body and provides energy.
Reason (R): Respiration is an example of oxidation reaction.
Reason (R): Respiration is an example of oxidation reaction.
Correct Answer: B
Both are true statements. Cellular respiration involves the breakdown of glucose with oxygen to produce energy. This process is a form of oxidation. However, the reason is a general statement and doesn’t fully explain the specific biological process in the assertion.
Both are true statements. Cellular respiration involves the breakdown of glucose with oxygen to produce energy. This process is a form of oxidation. However, the reason is a general statement and doesn’t fully explain the specific biological process in the assertion.
Q60. Assertion (A): Red light travels faster in glass than green light.
Reason (R): The refractive index of glass is less for green light.
Reason (R): The refractive index of glass is less for green light.
Correct Answer: C
Assertion is true. The speed of light in a medium is inversely proportional to the refractive index. The refractive index of glass is lower for longer wavelengths (like red) than for shorter wavelengths (like green). Therefore, red light travels faster. The reason is false, as the refractive index for green light is higher than for red light.
Assertion is true. The speed of light in a medium is inversely proportional to the refractive index. The refractive index of glass is lower for longer wavelengths (like red) than for shorter wavelengths (like green). Therefore, red light travels faster. The reason is false, as the refractive index for green light is higher than for red light.
Q61. Assertion (A): The light of violet colour deviates the most and the light of red colour the least,
while passing through a prism.
Reason (R): For a prism material, refractive index is highest for red light and lowest for the violet light.
Reason (R): For a prism material, refractive index is highest for red light and lowest for the violet light.
Correct Answer: C
Assertion is true. The reason is false; the refractive index of a material is highest for violet light (shorter wavelength) and lowest for red light (longer wavelength). This difference in refractive index causes the different degrees of deviation.
Assertion is true. The reason is false; the refractive index of a material is highest for violet light (shorter wavelength) and lowest for red light (longer wavelength). This difference in refractive index causes the different degrees of deviation.
Q62. Assertion (A): The compound prepared from gypsum on heating it at 373 K, is known as Plaster of Paris.
Reason (R): Plaster of Paris is used in hospitals mainly as plaster for supporting fractured bones in the right position. In dentistry, it is used for making casts.
Reason (R): Plaster of Paris is used in hospitals mainly as plaster for supporting fractured bones in the right position. In dentistry, it is used for making casts.
Correct Answer: B
Both are true statements. The assertion describes how Plaster of Paris is made, and the reason describes its common uses. However, the use of Plaster of Paris does not explain its method of preparation.
Both are true statements. The assertion describes how Plaster of Paris is made, and the reason describes its common uses. However, the use of Plaster of Paris does not explain its method of preparation.
Q63. Assertion (A): Bleaching powder is CaOCl2, and is prepared from chlorine and slaked lime.
Reason (R): Bleaching powder can be used for bleaching, disinfecting, oxidation.
Reason (R): Bleaching powder can be used for bleaching, disinfecting, oxidation.
Correct Answer: B
Both statements are true. The assertion correctly identifies the chemical and its preparation. The reason correctly lists its uses. However, the uses do not explain the preparation.
Both statements are true. The assertion correctly identifies the chemical and its preparation. The reason correctly lists its uses. However, the uses do not explain the preparation.
Q64. Assertion (A): Iron is the most widely used metal. But it is never used in its pure state.
Reason (R): Pure iron is very soft and stretches easily when hot.
Reason (R): Pure iron is very soft and stretches easily when hot.
Correct Answer: A
Pure iron is not used for most applications because it is soft and not very strong. It is typically alloyed with carbon (to make steel) and other elements to improve its properties. The reason correctly explains why pure iron is not used.
Pure iron is not used for most applications because it is soft and not very strong. It is typically alloyed with carbon (to make steel) and other elements to improve its properties. The reason correctly explains why pure iron is not used.
Q65. Assertion (A): Aluminium oxide and zinc oxide are acidic in nature.
Reason (R): Amphoteric nature means that substance have both acidic and basic character.
Reason (R): Amphoteric nature means that substance have both acidic and basic character.
Correct Answer: D
Assertion is false; aluminium oxide and zinc oxide are amphoteric, not acidic. The reason is true; it correctly defines amphoteric nature.
Assertion is false; aluminium oxide and zinc oxide are amphoteric, not acidic. The reason is true; it correctly defines amphoteric nature.
Q66. Assertion (A): Mirror Formula cannot be used for Plane Mirrors.
Reason (R): Plane Mirror is a Spherical Mirror of Infinite Focal Length.
Reason (R): Plane Mirror is a Spherical Mirror of Infinite Focal Length.
Correct Answer: D
Assertion is false. The mirror formula can be used for plane mirrors. Reason is true; a plane mirror can be considered a spherical mirror with an infinite radius of curvature, and thus an infinite focal length. If you substitute f = ∞ into the mirror formula (1/f = 0), you get v = -u, which is correct for a plane mirror.
Assertion is false. The mirror formula can be used for plane mirrors. Reason is true; a plane mirror can be considered a spherical mirror with an infinite radius of curvature, and thus an infinite focal length. If you substitute f = ∞ into the mirror formula (1/f = 0), you get v = -u, which is correct for a plane mirror.
Q67. Assertion (A): The organic compounds such as C6H12O6 and C2H5OH contain hydrogen but they do not
conduct electricity in the water.
Reason (R): Acids produce H3O+ ions in the solutions.
Reason (R): Acids produce H3O+ ions in the solutions.
Correct Answer: B
Both are true. Compounds like glucose and ethanol do not ionize in water to produce H+ ions, so their solutions do not conduct electricity. Acids, on the other hand, do produce H+ (or H3O+) ions, which allows their solutions to conduct electricity. The reason explains why acids conduct electricity, providing a contrast but not a direct explanation for the assertion.
Both are true. Compounds like glucose and ethanol do not ionize in water to produce H+ ions, so their solutions do not conduct electricity. Acids, on the other hand, do produce H+ (or H3O+) ions, which allows their solutions to conduct electricity. The reason explains why acids conduct electricity, providing a contrast but not a direct explanation for the assertion.
Q68. Assertion (A): Tracheal cartilage is present in the throat.
Reason (R): The larynx plays an important role in human speech.
Reason (R): The larynx plays an important role in human speech.
Correct Answer: B
Both are true statements about structures in the throat. Tracheal cartilages prevent the trachea from collapsing, while the larynx (voice box) is crucial for speech. They are both located in the same general area but have different primary functions.
Both are true statements about structures in the throat. Tracheal cartilages prevent the trachea from collapsing, while the larynx (voice box) is crucial for speech. They are both located in the same general area but have different primary functions.
Q69. Assertion (A): Chyme is the food which enters into the intestine from stomach.
Reason (R): Chyme is acidic in nature.
Reason (R): Chyme is acidic in nature.
Correct Answer: B
Both statements are true. Chyme is the semi-fluid mass of partly digested food that is expelled by the stomach into the duodenum. Due to the presence of hydrochloric acid in the stomach, chyme is highly acidic. The reason describes a property of chyme, but doesn’t explain what it is.
Both statements are true. Chyme is the semi-fluid mass of partly digested food that is expelled by the stomach into the duodenum. Due to the presence of hydrochloric acid in the stomach, chyme is highly acidic. The reason describes a property of chyme, but doesn’t explain what it is.
Q70. Assertion (A): C and N do not react with dil. HCl and dil. H2SO4.
Reason (R): Metals do not react with dil. HCl and dil. H2SO4.
Reason (R): Metals do not react with dil. HCl and dil. H2SO4.
Correct Answer: C
Assertion is true; Carbon (C) and Nitrogen (N) are non-metals and do not react with dilute acids to displace hydrogen. The reason is false; many metals (those above hydrogen in the reactivity series) do react with dilute acids.
Assertion is true; Carbon (C) and Nitrogen (N) are non-metals and do not react with dilute acids to displace hydrogen. The reason is false; many metals (those above hydrogen in the reactivity series) do react with dilute acids.
Q71. Assertion (A): Gold occurs in native state.
Reason (R): Gold is a reactive metal.
Reason (R): Gold is a reactive metal.
Correct Answer: C
Assertion is true; gold is found in its elemental form in nature. The reason is false; gold is one of the least reactive metals, which is why it is found in its native state.
Assertion is true; gold is found in its elemental form in nature. The reason is false; gold is one of the least reactive metals, which is why it is found in its native state.
Q72. Assertion (A): Decomposition of Calcium Carbonate is a type of chemical reaction.
Reason (R): Chemical reactions involve the breaking and making of bonds to produce new substances.
Reason (R): Chemical reactions involve the breaking and making of bonds to produce new substances.
Correct Answer: A
The decomposition of calcium carbonate is a chemical reaction because it involves breaking bonds in CaCO3 and forming new substances (CaO and CO2). The reason provides the fundamental definition of a chemical reaction, which correctly explains the assertion.
The decomposition of calcium carbonate is a chemical reaction because it involves breaking bonds in CaCO3 and forming new substances (CaO and CO2). The reason provides the fundamental definition of a chemical reaction, which correctly explains the assertion.
Q73. Assertion (A): The red light bends the least while the violet bends the most.
Reason (R): Red light has short wavelength whereas violet has long wavelength.
Reason (R): Red light has short wavelength whereas violet has long wavelength.
Correct Answer: C
Assertion is true. When white light is dispersed by a prism, violet light deviates the most and red light the least. The reason is false; red light has a long wavelength, and violet light has a short wavelength.
Assertion is true. When white light is dispersed by a prism, violet light deviates the most and red light the least. The reason is false; red light has a long wavelength, and violet light has a short wavelength.
Q74. Assertion (A): Silver Bromide is used in black and white photography.
Reason (R): Silver Bromide decomposes in the presence of sunlight.
Reason (R): Silver Bromide decomposes in the presence of sunlight.
Correct Answer: A
The property of silver bromide to decompose when exposed to light (photochemical decomposition) is the principle behind its use in photographic film.
The property of silver bromide to decompose when exposed to light (photochemical decomposition) is the principle behind its use in photographic film.
Q75. Assertion (A): In double displacement reactions, no precipitate is formed.
Reason (R): Barium Sulphate is precipitated during the double displacement reaction between Sodium Sulphate and Barium Chloride.
Reason (R): Barium Sulphate is precipitated during the double displacement reaction between Sodium Sulphate and Barium Chloride.
Correct Answer: D
Assertion is false. Many double displacement reactions are precipitation reactions. The reason is a true statement and serves as a direct counterexample to the assertion.
Assertion is false. Many double displacement reactions are precipitation reactions. The reason is a true statement and serves as a direct counterexample to the assertion.
Q76. Assertion (A): Phenolphthalein is a synthetic acid-base indicator.
Reason (R): Phenolphthalein does not give any colour with acids but gives pink colour with bases.
Reason (R): Phenolphthalein does not give any colour with acids but gives pink colour with bases.
Correct Answer: A
Phenolphthalein is indeed a man-made (synthetic) indicator. Its function as an indicator is based on its property of being colourless in acidic/neutral solutions and turning pink in basic solutions. The reason perfectly describes its behaviour, explaining why it’s used as an indicator.
Phenolphthalein is indeed a man-made (synthetic) indicator. Its function as an indicator is based on its property of being colourless in acidic/neutral solutions and turning pink in basic solutions. The reason perfectly describes its behaviour, explaining why it’s used as an indicator.
Q77. Assertion (A): The left atrium and left ventricle are completely separated from the right atrium and
the right ventricle.
Reason (R): oxygenated and deoxygenated blood never mix with each other inside the heart.
Reason (R): oxygenated and deoxygenated blood never mix with each other inside the heart.
Correct Answer: A
The septum separates the left and right sides of the heart. This separation is crucial for preventing the mixing of oxygenated blood (on the left side) and deoxygenated blood (on the right side), ensuring efficient oxygen delivery to the body.
The septum separates the left and right sides of the heart. This separation is crucial for preventing the mixing of oxygenated blood (on the left side) and deoxygenated blood (on the right side), ensuring efficient oxygen delivery to the body.
Q78. Assertion (A): NH4Cl is an acidic salt.
Reason (R): NH4Cl is the salt of hydrochloric acid and ammonium hydroxide.
Reason (R): NH4Cl is the salt of hydrochloric acid and ammonium hydroxide.
Correct Answer: A
Ammonium chloride (NH4Cl) is a salt formed from a strong acid (HCl) and a weak base (NH4OH). When dissolved in water, it undergoes hydrolysis to produce an acidic solution. The reason correctly identifies its parent acid and base, which explains its acidic nature.
Ammonium chloride (NH4Cl) is a salt formed from a strong acid (HCl) and a weak base (NH4OH). When dissolved in water, it undergoes hydrolysis to produce an acidic solution. The reason correctly identifies its parent acid and base, which explains its acidic nature.
Q79. Assertion (A): When dil. H2SO4 is added to zinc granules, a physical change is observed.
Reason (R): A gas is evolved which burns with ‘pop’ sound.
Reason (R): A gas is evolved which burns with ‘pop’ sound.
Correct Answer: D
Assertion is false. The reaction between zinc and sulphuric acid is a chemical change, as new substances (zinc sulphate and hydrogen gas) are formed. The reason is true; the gas evolved is hydrogen, which characteristically burns with a ‘pop’ sound.
Assertion is false. The reaction between zinc and sulphuric acid is a chemical change, as new substances (zinc sulphate and hydrogen gas) are formed. The reason is true; the gas evolved is hydrogen, which characteristically burns with a ‘pop’ sound.
Q80. Assertion (A): MgO exists in liquid state.
Reason (R): The electrostatic forces of attraction between Mg2+ and O2- ions constitute ionic bond.
Reason (R): The electrostatic forces of attraction between Mg2+ and O2- ions constitute ionic bond.
Correct Answer: D
Assertion is false; Magnesium oxide (MgO) is an ionic compound and exists as a solid at room temperature due to the strong electrostatic forces. The reason is true; the bond in MgO is indeed an ionic bond formed between Mg2+ and O2- ions.
Assertion is false; Magnesium oxide (MgO) is an ionic compound and exists as a solid at room temperature due to the strong electrostatic forces. The reason is true; the bond in MgO is indeed an ionic bond formed between Mg2+ and O2- ions.
Q81. Assertion (A): kidneys purify blood.
Reason (R): renal vein has more Oxygen than renal artery.
Reason (R): renal vein has more Oxygen than renal artery.
Correct Answer: C
Assertion is true; kidneys filter waste products from the blood. Reason is false; the renal artery supplies oxygenated blood to the kidneys for their own metabolic needs. The renal vein carries deoxygenated blood away from the kidneys after oxygen has been used by the kidney cells.
Assertion is true; kidneys filter waste products from the blood. Reason is false; the renal artery supplies oxygenated blood to the kidneys for their own metabolic needs. The renal vein carries deoxygenated blood away from the kidneys after oxygen has been used by the kidney cells.
Q82. Assertion (A): Refractive index of glass with respect to air is different for red light and violet
light.
Reason (R): Refractive Index of a pair of medium does not depend on the wavelength of the light used.
Reason (R): Refractive Index of a pair of medium does not depend on the wavelength of the light used.
Correct Answer: C
Assertion is true. This phenomenon is called dispersion, and it’s why prisms work. The reason is false; refractive index is dependent on the wavelength of light.
Assertion is true. This phenomenon is called dispersion, and it’s why prisms work. The reason is false; refractive index is dependent on the wavelength of light.
Q83. Assertion (A): Washing soda is a chemical compound that can be used to remove stubborn stains from
laundry.
Reason (R): The sodium carbonate in washing soda ‘softens’ water.
Reason (R): The sodium carbonate in washing soda ‘softens’ water.
Correct Answer: B
Both are true. Washing soda (sodium carbonate) is a cleaning agent. It also softens water by precipitating calcium and magnesium ions. While water softening helps in cleaning, it’s not the sole reason it removes stains (it also has alkaline properties that help break down grease).
Both are true. Washing soda (sodium carbonate) is a cleaning agent. It also softens water by precipitating calcium and magnesium ions. While water softening helps in cleaning, it’s not the sole reason it removes stains (it also has alkaline properties that help break down grease).
Q84. Assertion (A): A Concave mirror of radius R is placed in water. Its focal length differs in Air and
Water.
Reason (R): Focal length of concave mirror is equal to R/2.
Reason (R): Focal length of concave mirror is equal to R/2.
Correct Answer: D
Assertion is false. The focal length of a spherical mirror depends only on its radius of curvature (f = R/2) and not on the refractive index of the surrounding medium. The focal length of a lens changes with the medium, but not a mirror. The reason is a true statement.
Assertion is false. The focal length of a spherical mirror depends only on its radius of curvature (f = R/2) and not on the refractive index of the surrounding medium. The focal length of a lens changes with the medium, but not a mirror. The reason is a true statement.
Q85. Assertion (A): Oxidation and reduction take place simultaneously in a reaction.
Reason (R): All chemical reactions are redox reactions.
Reason (R): All chemical reactions are redox reactions.
Correct Answer: C
Assertion is true; oxidation (loss of electrons) and reduction (gain of electrons) are coupled processes and always occur together in what is called a redox reaction. The reason is false; not all reactions are redox reactions (e.g., acid-base neutralizations, precipitation reactions).
Assertion is true; oxidation (loss of electrons) and reduction (gain of electrons) are coupled processes and always occur together in what is called a redox reaction. The reason is false; not all reactions are redox reactions (e.g., acid-base neutralizations, precipitation reactions).
Q86. Assertion (A): a mammal has double circulation.
Reason (R): higher energy need due to endothermy.
Reason (R): higher energy need due to endothermy.
Correct Answer: A
Mammals are endothermic (warm-blooded) and have high energy demands to maintain a constant body temperature. Double circulation (separate pulmonary and systemic circuits) is a highly efficient system that ensures oxygenated blood is supplied to the body, meeting these high energy needs.
Mammals are endothermic (warm-blooded) and have high energy demands to maintain a constant body temperature. Double circulation (separate pulmonary and systemic circuits) is a highly efficient system that ensures oxygenated blood is supplied to the body, meeting these high energy needs.
Q87. Assertion (A): Copper displaces silver from silver nitrate solution.
Reason (R): Copper is more reactive than silver.
Reason (R): Copper is more reactive than silver.
Correct Answer: A
In the reactivity series, copper is placed above silver. This means copper is more reactive and can displace silver from its salt solution, like silver nitrate.
In the reactivity series, copper is placed above silver. This means copper is more reactive and can displace silver from its salt solution, like silver nitrate.
Q88. Assertion (A): Different metals have different reactivities with water and dilute acids.
Reason (R): Reactivity of a metal depends on its position in the reactivity series.
Reason (R): Reactivity of a metal depends on its position in the reactivity series.
Correct Answer: A
The reactivity series is an arrangement of metals in order of their reactivity. A metal’s position in this series determines how vigorously it will react with substances like water and acids. The reason correctly explains the assertion.
The reactivity series is an arrangement of metals in order of their reactivity. A metal’s position in this series determines how vigorously it will react with substances like water and acids. The reason correctly explains the assertion.
Q89. Assertion (A): Acidification of water decreases its conductivity during electrolysis.
Reason (R): H ions are released which hinder the flow of charges.
Reason (R): H ions are released which hinder the flow of charges.
Correct Answer: D
Assertion is false. Pure water is a poor conductor of electricity. Adding a small amount of acid increases the concentration of ions (H+ and the acid’s anion), which significantly increases its conductivity. The reason is also false; H+ ions are charge carriers and facilitate, not hinder, the flow of charge.
Assertion is false. Pure water is a poor conductor of electricity. Adding a small amount of acid increases the concentration of ions (H+ and the acid’s anion), which significantly increases its conductivity. The reason is also false; H+ ions are charge carriers and facilitate, not hinder, the flow of charge.
Q90. Assertion (A): Fatty foods taste the same even after long periods of exposure to air.
Reason (R): We should store oily foods in air tight containers.
Reason (R): We should store oily foods in air tight containers.
Correct Answer: D
Assertion is false. Fatty foods undergo oxidation (rancidity) when exposed to air, which changes their taste and smell. The reason is true; storing them in airtight containers prevents this oxidation.
Assertion is false. Fatty foods undergo oxidation (rancidity) when exposed to air, which changes their taste and smell. The reason is true; storing them in airtight containers prevents this oxidation.
Q91. Assertion (A): Virtual images are always erect.
Reason (R): Virtual images are formed by converging lenses only.
Reason (R): Virtual images are formed by converging lenses only.
Correct Answer: C
Assertion is true; a virtual image is always upright (erect) with respect to the object. The reason is false; virtual images can be formed by converging lenses, diverging lenses, plane mirrors, and convex mirrors.
Assertion is true; a virtual image is always upright (erect) with respect to the object. The reason is false; virtual images can be formed by converging lenses, diverging lenses, plane mirrors, and convex mirrors.
Q92. Assertion (A): Soda-acid fire extinguisher contains sodium hydrogen carbonate and sulphuric acid.
Reason (R): Sulphuric acid mixes with sodium hydrogen carbonate solution and produces a lot of CO2 gas, which forms a blanket over fire and cuts it off from the supply of the air to the burning substance and the fire stops.
Reason (R): Sulphuric acid mixes with sodium hydrogen carbonate solution and produces a lot of CO2 gas, which forms a blanket over fire and cuts it off from the supply of the air to the burning substance and the fire stops.
Correct Answer: A
The assertion correctly identifies the reactants. The reason correctly describes the chemical reaction and the mechanism by which the extinguisher works: the produced CO2 gas displaces oxygen, extinguishing the fire.
The assertion correctly identifies the reactants. The reason correctly describes the chemical reaction and the mechanism by which the extinguisher works: the produced CO2 gas displaces oxygen, extinguishing the fire.
Q93. Assertion (A): NaOH reacts with zinc metal and produces hydrogen gas.
Reason (R): Acids react with active metals to produce hydrogen gas.
Reason (R): Acids react with active metals to produce hydrogen gas.
Correct Answer: B
Assertion is true; strong bases like NaOH can react with certain amphoteric metals like zinc to produce hydrogen gas. The reason is also a true statement, but it describes the reaction of acids, not bases. Therefore, it does not explain the assertion.
Assertion is true; strong bases like NaOH can react with certain amphoteric metals like zinc to produce hydrogen gas. The reason is also a true statement, but it describes the reaction of acids, not bases. Therefore, it does not explain the assertion.
Q94. Assertion (A): mammals and birds have four chambered heart.
Reason (R): mammals and birds are warm blooded.
Reason (R): mammals and birds are warm blooded.
Correct Answer: A
Being warm-blooded (endothermic) requires a high metabolic rate and an efficient supply of oxygen. A four-chambered heart prevents the mixing of oxygenated and deoxygenated blood, ensuring this efficiency, thus supporting a warm-blooded lifestyle.
Being warm-blooded (endothermic) requires a high metabolic rate and an efficient supply of oxygen. A four-chambered heart prevents the mixing of oxygenated and deoxygenated blood, ensuring this efficiency, thus supporting a warm-blooded lifestyle.
Q95. Assertion (A): Magnesium chloride is an ionic compound.
Reason (R): Metals and non-metals react by mutual transfer of electrons.
Reason (R): Metals and non-metals react by mutual transfer of electrons.
Correct Answer: A
Magnesium (a metal) transfers two electrons to two chlorine atoms (non-metals) to form MgCl2. This transfer of electrons is the definition of ionic bonding. The reason correctly explains the formation of the ionic compound in the assertion.
Magnesium (a metal) transfers two electrons to two chlorine atoms (non-metals) to form MgCl2. This transfer of electrons is the definition of ionic bonding. The reason correctly explains the formation of the ionic compound in the assertion.
Q96. Assertion (A): Sulphur dioxide and Sulphur trioxides are released during the decomposition of iron
sulphate.
Reason (R): This is an example of thermal decomposition.
Reason (R): This is an example of thermal decomposition.
Correct Answer: B
Both are true. Heating ferrous sulphate (FeSO4) crystals causes them to decompose into ferric oxide (Fe2O3), sulphur dioxide (SO2), and sulphur trioxide (SO3). This reaction, initiated by heat, is a thermal decomposition. However, the reason just classifies the reaction type, it doesn’t explain why those specific products are formed.
Both are true. Heating ferrous sulphate (FeSO4) crystals causes them to decompose into ferric oxide (Fe2O3), sulphur dioxide (SO2), and sulphur trioxide (SO3). This reaction, initiated by heat, is a thermal decomposition. However, the reason just classifies the reaction type, it doesn’t explain why those specific products are formed.
Q97. Assertion (A): pH=7 indicates pure water.
Reason (R): At the pH 7, [H+]=[OH-]=10^-7.
Reason (R): At the pH 7, [H+]=[OH-]=10^-7.
Correct Answer: A
A pH of 7 signifies a neutral solution. In pure water, the concentration of hydrogen ions [H+] is equal to the concentration of hydroxide ions [OH-], which is 10^-7 mol/L at 25°C. This equality is the definition of neutrality, so the reason correctly explains the assertion.
A pH of 7 signifies a neutral solution. In pure water, the concentration of hydrogen ions [H+] is equal to the concentration of hydroxide ions [OH-], which is 10^-7 mol/L at 25°C. This equality is the definition of neutrality, so the reason correctly explains the assertion.
Q98. Assertion (A): Rainbow is an example of the dispersion of sunlight by the water droplets.
Reason (R): Light of shorter wavelength is scattered much more than light of larger wavelength.
Reason (R): Light of shorter wavelength is scattered much more than light of larger wavelength.
Correct Answer: B
The assertion is true. The reason describes Rayleigh scattering, which explains why the sky is blue. While it is a true statement about light, it does not explain the phenomenon of dispersion in a rainbow.
The assertion is true. The reason describes Rayleigh scattering, which explains why the sky is blue. While it is a true statement about light, it does not explain the phenomenon of dispersion in a rainbow.
Q99. Assertion (A): Baking powder is used in making cake instead of using only baking soda.
Reason (R): Baking powder contains Tartaric acid which reacts with sodium carbonate and removes bitter taste.
Reason (R): Baking powder contains Tartaric acid which reacts with sodium carbonate and removes bitter taste.
Correct Answer: A
Baking soda (NaHCO3) decomposes on heating to produce CO2 (which makes the cake rise) and sodium carbonate (Na2CO3), which is bitter. Baking powder contains baking soda and a mild acid like tartaric acid. This acid neutralizes the bitter sodium carbonate, improving the taste of the cake.
Baking soda (NaHCO3) decomposes on heating to produce CO2 (which makes the cake rise) and sodium carbonate (Na2CO3), which is bitter. Baking powder contains baking soda and a mild acid like tartaric acid. This acid neutralizes the bitter sodium carbonate, improving the taste of the cake.
Q100. Assertion (A): Large Concave mirrors are used to concentrate sunlight to produce heat in solar
cookers.
Reason (R): Concave mirror converges the light rays falling on it to a point.
Reason (R): Concave mirror converges the light rays falling on it to a point.
Correct Answer: A
A concave mirror is a converging mirror. This property allows it to collect parallel rays of sunlight and focus them onto a single point (the focus), generating significant heat, which is the principle of a solar cooker.
A concave mirror is a converging mirror. This property allows it to collect parallel rays of sunlight and focus them onto a single point (the focus), generating significant heat, which is the principle of a solar cooker.
Q101. Assertion (A): Convex mirror is preferred for rear view mirrors in vehicles.
Reason (R): The field view of a convex mirror is lesser than that of concave mirror.
Reason (R): The field view of a convex mirror is lesser than that of concave mirror.
Correct Answer: C
Assertion is true. The reason is false; a convex mirror provides a much wider field of view than a concave or plane mirror of the same size, which is precisely why it is used for rear-view mirrors.
Assertion is true. The reason is false; a convex mirror provides a much wider field of view than a concave or plane mirror of the same size, which is precisely why it is used for rear-view mirrors.
Q102. Assertion (A): Sun looks reddish at sunrise and sunset.
Reason (R): Sun rays have to pass through smaller distance in atmosphere.
Reason (R): Sun rays have to pass through smaller distance in atmosphere.
Correct Answer: C
Assertion is true. The reason is false; at sunrise and sunset, sunlight has to travel through a much larger distance in the atmosphere. This causes most of the shorter wavelengths (like blue and green) to be scattered away, leaving the longer wavelengths (red and orange) to reach our eyes.
Assertion is true. The reason is false; at sunrise and sunset, sunlight has to travel through a much larger distance in the atmosphere. This causes most of the shorter wavelengths (like blue and green) to be scattered away, leaving the longer wavelengths (red and orange) to reach our eyes.
🧑🏫 Topics Covered in This Quiz
Our Class 10 Science Assertion and Reason Questions cover all three subjects:
🔹 Physics
- Light – Reflection and Refraction
- Human Eye and Colourful World
- Electricity
- Magnetic Effects of Electric Current
- Sources of Energy
🔹 Chemistry
- Chemical Reactions and Equations
- Acids, Bases, and Salts
- Metals and Non-Metals
- Carbon and its Compounds
- Periodic Classification of Elements
🔹 Biology
- Life Processes
- Control and Coordination
- How Do Organisms Reproduce?
- Heredity and Evolution
- Our Environment
📝 Assertion and Reasoning Quiz Format
- Total: 102 Questions
- Subject-wise and Chapter-wise arrangement
- Instant answer feedback after each question
- Designed as per latest CBSE Class 10 Science exam pattern
📥 Benefits of Using This Quiz
✔️ Free online quiz format – no need to download PDFs
✔️ Practice anytime, anywhere (mobile-friendly)
✔️ Solutions explained in simple language
✔️ Covers Physics, Chemistry, and Biology in one place
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