Assertion and Reason Questions and Answers

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.

Cotton is grown on the alluvium of Punjab, Haryana and western Uttar Pradesh as well as on black soil, and the fertility of alluvial soil - renewed each year by river silt - is what supports the crop 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.

HIV mutates rapidly, particularly in the surface proteins a vaccine would have to target, so no vaccine has been able to keep pace with the strains in circulation. The changing genetic code is the very reason no vaccine exists. 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 pigment responsible is chlorophyll, held in chloroplasts. Chromoplasts are the plastids that carry the red, orange and yellow pigments of flowers and fruits. R is false.

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 in the atmosphere raises the global temperature - and warmer air and oceans are what melt the polar ice. The rise in temperature is the mechanism linking 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.

Marine fossils - ammonites, corals and shells - are found high in the Himalayan rocks, and the only way they could have got there is for those rocks to have been laid down under the sea before the collision of the Indian and Eurasian plates lifted them. 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.

Once fruit or vegetable is cut, the exposed surfaces lose vitamin C rapidly to oxidation, helped by light and by enzymes released when the cells are broken. Losing that food value is exactly why cut produce should not be left standing. Both are true and R explains A.

Answer: C

Correct answer: A is true but R is false.

The Indian judiciary is independent of the executive - judges’ tenure, salaries and removal are protected by the Constitution - so A is true. R states the opposite of independence: a judiciary that existed to favour the government would not be independent at all. R is false.

Answer: A

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

Air temperature falls by roughly \( 6.5^{\circ}\mathrm{C} \) for every kilometre of altitude, because the air aloft is thinner and further from the ground that warms it. That fall is precisely why mountains feel colder than the plains below. Both are true and R explains A.

Answer: C

Correct answer: A is true but R is false.

Weeds must indeed be kept out of a crop, so A is true. But the reason given is not the real one: weeds do their damage by competing for water, nutrients and light, and by harbouring pests - not merely by occupying space. R is false.