Assertion and Reason Questions and Answers

Answer: A

Correct answer: Both A and R are true and R is the correct explanation of A.

Plaster of Paris, calcium sulphate hemihydrate, takes up water and sets into a hard mass of gypsum within minutes. That is precisely why a bandage soaked in it can be moulded round a limb and left to harden, holding the bone still. Both are true and R explains A.

Answer: C

Correct answer: A is true but R is false.

CFCs have been phased out under the Montreal Protocol, so A is true. But they do not themselves cause cancer: they destroy stratospheric ozone, and it is the extra ultraviolet radiation reaching the ground that raises the risk of skin cancer. R is false as a direct reason.

Answer: B

Correct answer: Both A and R are true but R is NOT the correct explanation of A.

Both statements are true, but being an alloy of copper and tin is not why bronze is chosen for statues. It is chosen because it flows well into a mould, expands slightly as it sets so as to take up fine detail, and resists corrosion out of doors. R does not explain A.

Answer: A

Correct answer: Both A and R are true and R is the correct explanation of A.

Black money circulates outside the tax and banking system and adds to the demand chasing goods without adding to their supply, which pushes prices up. Failure to check its growth therefore feeds inflation directly. Both are true and R explains A.

Answer: C

Correct answer: A is true but R is false.

Leaves are green, so A is true. But the green pigment is chlorophyll, carried in chloroplasts; chromoplasts hold the red, orange and yellow pigments of flowers and fruits. R is false.

Answer: D

Correct answer: A is false but R is true.

White surfaces do reflect radiant heat well, so R is true. But that is why white is worn in summer; in winter dark clothes, which absorb heat, are preferred. A is false.

Answer: C

Correct answer: A is true but R is false.

A leak can be smelt, so A is true. But LPG is odourless in itself: ethyl mercaptan is added in tiny quantities precisely so that leaks announce themselves. R is false as stated.

Answer: A

Correct answer: Both A and R are true and R is the correct explanation of A.

Simla is colder than Delhi, and it stands at about 2200 m against Delhi’s 220 m. Air cools by roughly \( 6.5^{\circ}\mathrm{C} \) for every kilometre of ascent, so the altitude difference accounts for the temperature difference directly. Both are true and R explains A.

Answer: B

Correct answer: Both A and R are true but R is NOT the correct explanation of A.

Both statements are true, but the reason given is the wrong half of the cycle. Land heats quickly by day, which drives the sea breeze; at night it also cools quickly, so the air over it becomes denser and flows out to sea. It is the rapid cooling, not the rapid heating, that produces the land breeze. R does not explain A.

Answer: A

Correct answer: Both A and R are true and R is the correct explanation of A.

Ice forms only at the surface, and being less dense than water it floats there, insulating the water beneath. The layer below stays liquid at about \( 4^{\circ}\mathrm{C} \), where water is densest, so the fish survive. Both are true and R explains A.