Q.1 Assertion (A): All mammals have hair. Reason (R): Hair is a characteristic feature of mammals.
A is true, R is true and R is the correct explanation of A
A is true, R is true but R is not the correct explanation of A
A is true, R is false
A is false, R is true
Explanation - Hair is a characteristic feature that distinguishes mammals from other animals, so the reason correctly explains the assertion.
Correct answer is: A is true, R is true and R is the correct explanation of A
Q.2 Assertion (A): The heart pumps blood to the entire body. Reason (R): The lungs oxygenate the blood before it reaches the heart.
A is true, R is true and R is the correct explanation of A
A is true, R is true but R is not the correct explanation of A
A is true, R is false
A is false, R is true
Explanation - The heart pumps blood to the entire body, which is true. The reason is also true but does not directly explain why the heart pumps blood to the body.
Correct answer is: A is true, R is true but R is not the correct explanation of A
Q.3 Assertion (A): Enzymes speed up biochemical reactions. Reason (R): Enzymes are proteins.
A is true, R is true and R is the correct explanation of A
A is true, R is true but R is not the correct explanation of A
A is true, R is false
A is false, R is true
Explanation - Enzymes do speed up reactions (true), and while most enzymes are proteins (true), being a protein is not the reason they act as catalysts.
Correct answer is: A is true, R is true but R is not the correct explanation of A
Q.4 Assertion (A): Mercury is used in thermometers. Reason (R): Mercury has a high coefficient of expansion.
A is true, R is true and R is the correct explanation of A
A is true, R is true but R is not the correct explanation of A
A is true, R is false
A is false, R is true
Explanation - Mercury expands uniformly with temperature changes, making it suitable for precise temperature measurement.
Correct answer is: A is true, R is true and R is the correct explanation of A
Q.5 Assertion (A): DNA is the genetic material in humans. Reason (R): DNA consists of nucleotides containing adenine, guanine, cytosine, and thymine.
A is true, R is true and R is the correct explanation of A
A is true, R is true but R is not the correct explanation of A
A is true, R is false
A is false, R is true
Explanation - DNA is indeed the genetic material. Its nucleotide composition is correct, but it does not explain why DNA is the genetic material.
Correct answer is: A is true, R is true but R is not the correct explanation of A
Q.6 Assertion (A): Sound cannot travel in a vacuum. Reason (R): Sound requires a medium to propagate.
A is true, R is true and R is the correct explanation of A
A is true, R is true but R is not the correct explanation of A
A is true, R is false
A is false, R is true
Explanation - Sound is a mechanical wave and needs a material medium to travel; hence the reason directly explains the assertion.
Correct answer is: A is true, R is true and R is the correct explanation of A
Q.7 Assertion (A): Insulin regulates blood sugar levels. Reason (R): Insulin is secreted by the pancreas.
A is true, R is true and R is the correct explanation of A
A is true, R is true but R is not the correct explanation of A
A is true, R is false
A is false, R is true
Explanation - Insulin does regulate blood sugar (true). It is secreted by the pancreas (true), but the source does not explain its function.
Correct answer is: A is true, R is true but R is not the correct explanation of A
Q.8 Assertion (A): Metals are good conductors of electricity. Reason (R): Metals have free electrons.
A is true, R is true and R is the correct explanation of A
A is true, R is true but R is not the correct explanation of A
A is true, R is false
A is false, R is true
Explanation - Free electrons in metals allow them to conduct electricity efficiently, directly explaining the assertion.
Correct answer is: A is true, R is true and R is the correct explanation of A
Q.9 Assertion (A): Boiling point of water decreases with altitude. Reason (R): Atmospheric pressure decreases with altitude.
A is true, R is true and R is the correct explanation of A
A is true, R is true but R is not the correct explanation of A
A is true, R is false
A is false, R is true
Explanation - Lower atmospheric pressure at higher altitudes reduces the boiling point of water; the reason directly explains the assertion.
Correct answer is: A is true, R is true and R is the correct explanation of A
Q.10 Assertion (A): Vaccines prevent diseases. Reason (R): Vaccines stimulate the immune system to produce antibodies.
A is true, R is true and R is the correct explanation of A
A is true, R is true but R is not the correct explanation of A
A is true, R is false
A is false, R is true
Explanation - Vaccines work by triggering antibody production, which prevents diseases; the reason correctly explains the assertion.
Correct answer is: A is true, R is true and R is the correct explanation of A
Q.11 Assertion (A): Sound travels faster in water than in air. Reason (R): Water is denser than air.
A is true, R is true and R is the correct explanation of A
A is true, R is true but R is not the correct explanation of A
A is true, R is false
A is false, R is true
Explanation - Density and elasticity of the medium affect sound speed; higher density and elasticity of water allows faster sound propagation than in air.
Correct answer is: A is true, R is true and R is the correct explanation of A
Q.12 Assertion (A): Carbon dioxide is essential for photosynthesis. Reason (R): Plants convert CO2 and water into glucose in presence of sunlight.
A is true, R is true and R is the correct explanation of A
A is true, R is true but R is not the correct explanation of A
A is true, R is false
A is false, R is true
Explanation - CO2 is a raw material for photosynthesis; the reason describes the process, directly explaining the assertion.
Correct answer is: A is true, R is true and R is the correct explanation of A
Q.13 Assertion (A): Alcohol increases reaction time. Reason (R): Alcohol is a depressant that slows down the central nervous system.
A is true, R is true and R is the correct explanation of A
A is true, R is true but R is not the correct explanation of A
A is true, R is false
A is false, R is true
Explanation - Alcohol slows CNS activity, which increases reaction time; the reason explains the assertion.
Correct answer is: A is true, R is true and R is the correct explanation of A
Q.14 Assertion (A): The sky appears blue. Reason (R): Short wavelength light is scattered more by air molecules than long wavelength light.
A is true, R is true and R is the correct explanation of A
A is true, R is true but R is not the correct explanation of A
A is true, R is false
A is false, R is true
Explanation - Rayleigh scattering causes shorter wavelengths (blue) to scatter more, making the sky appear blue; reason directly explains the assertion.
Correct answer is: A is true, R is true and R is the correct explanation of A
Q.15 Assertion (A): Iron rusts in presence of water and oxygen. Reason (R): Rust is hydrated iron(III) oxide.
A is true, R is true and R is the correct explanation of A
A is true, R is true but R is not the correct explanation of A
A is true, R is false
A is false, R is true
Explanation - Iron rusts when exposed to water and oxygen (true). Rust's composition is true but does not explain the process of rusting.
Correct answer is: A is true, R is true but R is not the correct explanation of A
Q.16 Assertion (A): Lightning never strikes the same place twice. Reason (R): Lightning follows a random path.
A is true, R is true and R is the correct explanation of A
A is true, R is true but R is not the correct explanation of A
A is true, R is false
A is false, R is true
Explanation - Lightning can strike the same place multiple times. Lightning's path is random, so reason is true, assertion is false.
Correct answer is: A is false, R is true
Q.17 Assertion (A): Vitamin D is produced in human skin. Reason (R): Ultraviolet rays from sunlight convert 7-dehydrocholesterol to vitamin D3.
A is true, R is true and R is the correct explanation of A
A is true, R is true but R is not the correct explanation of A
A is true, R is false
A is false, R is true
Explanation - UV rays convert 7-dehydrocholesterol to vitamin D3 in skin, directly explaining the assertion.
Correct answer is: A is true, R is true and R is the correct explanation of A
Q.18 Assertion (A): Water boils at 100°C at sea level. Reason (R): Boiling point depends on atmospheric pressure.
A is true, R is true and R is the correct explanation of A
A is true, R is true but R is not the correct explanation of A
A is true, R is false
A is false, R is true
Explanation - Boiling point is the temperature at which vapor pressure equals atmospheric pressure. At sea level, water boils at 100°C; reason explains the assertion.
Correct answer is: A is true, R is true and R is the correct explanation of A
Q.19 Assertion (A): Antibiotics do not work against viruses. Reason (R): Viruses lack cellular structure and metabolic machinery.
A is true, R is true and R is the correct explanation of A
A is true, R is true but R is not the correct explanation of A
A is true, R is false
A is false, R is true
Explanation - Antibiotics target bacterial cell machinery. Viruses lack this machinery, so antibiotics are ineffective; reason explains assertion.
Correct answer is: A is true, R is true and R is the correct explanation of A
Q.20 Assertion (A): Sodium chloride dissolves in water. Reason (R): NaCl is an ionic compound and water is a polar solvent.
A is true, R is true and R is the correct explanation of A
A is true, R is true but R is not the correct explanation of A
A is true, R is false
A is false, R is true
Explanation - Polar water molecules interact with Na+ and Cl- ions, dissolving NaCl; reason explains assertion directly.
Correct answer is: A is true, R is true and R is the correct explanation of A
Q.21 Assertion (A): Earth’s atmosphere protects us from meteoroids. Reason (R): Friction with air burns most meteoroids before reaching surface.
A is true, R is true and R is the correct explanation of A
A is true, R is true but R is not the correct explanation of A
A is true, R is false
A is false, R is true
Explanation - Air friction causes meteoroids to burn, protecting Earth; reason directly explains assertion.
Correct answer is: A is true, R is true and R is the correct explanation of A
Q.22 Assertion (A): Alcohol is flammable. Reason (R): Alcohol molecules contain carbon and hydrogen bonds.
A is true, R is true and R is the correct explanation of A
A is true, R is true but R is not the correct explanation of A
A is true, R is false
A is false, R is true
Explanation - C-H bonds in alcohol release energy on combustion, making it flammable; reason explains assertion.
Correct answer is: A is true, R is true and R is the correct explanation of A
Q.23 Assertion (A): Earth has seasons. Reason (R): Earth’s axis is tilted relative to its orbital plane.
A is true, R is true and R is the correct explanation of A
A is true, R is true but R is not the correct explanation of A
A is true, R is false
A is false, R is true
Explanation - Tilted axis causes varying sunlight angles, creating seasons; reason directly explains assertion.
Correct answer is: A is true, R is true and R is the correct explanation of A
Q.24 Assertion (A): Neon lights emit colored light. Reason (R): Neon atoms emit photons when excited electrons return to lower energy levels.
A is true, R is true and R is the correct explanation of A
A is true, R is true but R is not the correct explanation of A
A is true, R is false
A is false, R is true
Explanation - Excited neon electrons emit photons of specific wavelengths, producing colored light; reason explains assertion.
Correct answer is: A is true, R is true and R is the correct explanation of A