Assertion and Reason Questions and Answers

Answer: A

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

Carbon monoxide binds to haemoglobin about 200 times more readily than oxygen does, forming carboxyhaemoglobin, which cannot carry oxygen. The blood is therefore left unable to supply the tissues, which is why the gas is lethal. Both are true and R explains A.

Answer: C

When in winter, hot water is poured in the glass tumbler. its inner surface tends to expand while the Outer surface in contact with cold atmosphere does not. This opposite interaction causes the tumbler to break. 

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.