Assertion and Reason Questions and Answers

Answer: A

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

Watt’s engine was built for the task of draining flooded mines, and his separate condenser reduced its fuel consumption so far that the engine became commercially practical. The mining problem is precisely what drove its development. Both are true and R explains A.

Answer: A

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

Carbon dioxide traps outgoing infrared radiation, so more of it raises the global temperature - and warmer air and oceans are what melt the polar ice. The temperature rise is the mechanism connecting the two. Both are true and R explains A.

Answer: A

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

Tamil Nadu receives most of its rain between October and December, when the retreating monsoon winds blow from the north-east across the Bay of Bengal and pick up moisture before striking the Coromandel coast. 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 they explain different properties. Graphite is slippery because its carbon atoms lie in flat sheets held together only by weak forces, so the layers slide over one another. The free electrons account for its electrical conductivity, not its lubricating action. R does not explain A.

Answer: C

Correct answer: A is true but R is false.

The Indian judiciary is independent of the executive, protected in tenure, salary and removal by the Constitution - so A is true. R describes the opposite of independence. R is false.

Answer: C

Correct answer: A is true but R is false.

An iron ball does float on mercury and sink in water, so A is true. But the reason is the reverse of what is stated: iron’s specific gravity, about 7.9, is less than mercury’s 13.6 and greater than water’s 1. R is false.

Answer: A

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

Copper has a very low resistivity, second only to silver among common metals, so it carries current with little loss as heat - and it is far cheaper than silver. That low resistance is exactly why it is chosen for wiring. Both are true and R explains A.

Answer: D

Correct answer: A is false but R is true.

Uranium does have a large, unstable nucleus, so R is true. But a heavy unstable nucleus splits: uranium undergoes nuclear fission, not fusion, which is the joining of light nuclei such as hydrogen. A is false.

Answer: A

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

Iron expands when heated, so rails laid tight in cool weather would buckle on a hot day. The gap left between lengths gives the metal room to expand, which is exactly why it is there. Both are true and R explains A.

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.