Assertion and Reason Questions and Answers

Answer: A

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

Common salt as sold contains traces of magnesium chloride, which is deliquescent - it absorbs moisture from the air until it dissolves in it. Pure sodium chloride does not do this, so the impurity is exactly the reason for the caking. Both are true and R explains A.

Answer: C

Correct answer: A is true but R is false.

A body immersed in a liquid does weigh less, so A is true. But the loss equals the weight of the liquid displaced, by Archimedes’ principle - not the “higher density” of that liquid, which need not be higher at all. R is false.

Answer: D

Correct answer: A is false but R is true.

Baking soda, sodium bicarbonate, is indeed alkaline, so R is true. But that is why it relieves acidity: it neutralises the excess hydrochloric acid in the stomach. It does not create acidity, so A is false.

Answer: A

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

The Himalayan rivers rise in glaciers and snowfields, which melt through the summer and keep the channels flowing even when the monsoon has failed. Peninsular rivers, fed only by rain, dry up. Both are true and R explains A.

Answer: D

Correct answer: Both A and R are false.

Amoebiasis is an infection of the intestine caused by the protozoan Entamoeba histolytica, spread through contaminated food and water - it is not tied to any occupation. Inhaled asbestos dust causes asbestosis, a quite different disease. Both A and R are false.

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.