For the Assertion (A) and Reason (R) below, choose the correct alternative.
Assertion (A) : We prefer to wear white clothes in winter.
Reason (R) : White clothes are good reflectors of heat.
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 exactly why white is worn in summer: in winter we prefer dark clothes, which absorb heat instead. A is false.
Please log in or register to report this question.
Assertion (A) : We feel comfortable in hot and humid climate.
Reason (R) : Sweat evaporates faster in humid climate
Answer: D
Correct answer: Both A and R are false.
Humid air is already close to saturation, so sweat evaporates more slowly, not faster - and because evaporation is what cools the body, hot humid weather feels oppressive rather than comfortable. Both A and R are false.
Please log in or register to report this question.
Assertion(A) : Tamil Nadu gets most of the rainfall in winter.
Reason (R) : Tamil Nadu gets rainfall from retreating monsoons.
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.
Please log in or register to report this question.
Assertion(A) : Graphite is slippery and used as a lubricant.
Reason (R) : Graphite has free electrons.
Answer: B
Graphite possesses a layer structure with two successive layers held by weak forces and able to slide over one another. So, graphite is slippery and this property finds its use as a lubricant. In graphite, each carbon atom is linked to three other carbon atoms while one electron in the carbon atom is delocalised. So, graphite has free electrons
Please log in or register to report this question.
Assertion (A) : Legumes revive the soil fertility.
Reason (R) : Microbes in the root nodules of legumes fix the atmospheric nitrogen.
Answer: A
Correct answer: Both A and R are true and R is the correct explanation of A.
Legumes carry Rhizobium bacteria in their root nodules, which convert atmospheric nitrogen into compounds the plant can use and leave the soil richer in nitrogen when the crop is ploughed in. That is precisely why legumes are grown in rotation, so both are true and R explains A.
Please log in or register to report this question.
Assertion (A) : Most of the Himalayan rivers are perennial.
Reason (R) : They are fed by melting snow.
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.
Please log in or register to report this question.
Assertion (A) : When the bus starts, the person inside it falls forward.
Reason (R) : The bus pushes the man forward.
Answer: D
Correct answer: Both A and R are false.
When a bus starts, the passenger’s body tends to stay at rest by inertia while the floor moves forward beneath him - so he falls backward, not forward, and nothing pushes him forward at all. Both A and R are false.
Please log in or register to report this question.
Assertion(A) : When common salt is kept open, it absorbs moisture from the air.
Reason (R) : Common salt contains magnesium chloride.
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.
Please log in or register to report this question.
Assertion (A) : Carbon monoxide when inhaled causes death.
Reason (R) : Carbon monoxide combines with haemoglobin.
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.
Please log in or register to report this question.
Assertion (A) : Glass tumbler breaks in winter when hot water is poured in it.
Reason (R) : When hot water is poured. the outer surface of glass expands.
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.
Please log in or register to report this question.
