Assertion and Reason Questions and Answers

Answer: C

Correct answer: Both A and R are false

A fuse is designed to melt and break the circuit when the current is excessive, so its wire is made of an alloy of tin and lead with a low melting point - and it must carry the normal current freely rather than resist it. Both A and R are false.

Answer: C

Correct answer: A is true but R is false.

Pluto is indeed the coldest of the bodies traditionally counted as planets, at around \( -230^{\circ}\mathrm{C} \), so A is true. But the cause is its enormous distance from the sun - sunlight there is some 1600 times fainter than at the earth - not the slant of the rays, which is what makes the earth’s poles cold. R is false.

Answer: A

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

In its upper course a river is steep and swift, so it carries most energy and cuts downward, forming gorges and V-shaped valleys. The speed of flow is precisely why erosion dominates there, while deposition takes over in the sluggish lower course. 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 the reason is too narrow. Rivers gave the early civilisations drinking water, fertile silt, a highway for transport and a defensible site - agriculture is only one of the reasons, not the whole explanation. R does not explain A.

Answer: A

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

Siddhartha left Kapilavastu after his marriage to Yasodhara and the birth of his son, having seen the sights of old age, sickness and death. His purpose was to renounce worldly attachments and seek release as an ascetic - which is exactly the reason given. Both are true and R explains A.

Answer: C

Correct answer: A is true but R is false.

Long soaking does spoil food, so A is true. But the vitamins washed away are the water-soluble ones - the B group and vitamin C. Vitamins A and D are fat-soluble and are not leached out by water. R is false.

Answer: D

Correct answer: A is false but R is true.

Earthworms do break the soil into fine crumbs, aerate it and enrich it with their castings, so R is true - and that is exactly why they are called the farmer’s friend. The assertion says the opposite of the truth, so A is false.

Answer: B

Correct answer: Both A and R are true but R is NOT the correct explanation of A.

Both statements are true, but harm to man is not the main reason DDT was abandoned. It persists for decades, accumulates up the food chain and thinned the eggshells of birds, and insects developed resistance to it - those are what ended its use. R does not explain A.

Answer: C

Correct answer: A is true but R is false.

Seed treatment with a fungicide is standard practice, so A is true. But untreated seed germinates perfectly well; the dressing protects the young seedling from soil-borne fungi such as smut and damping-off. R is false.

Answer: A

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

A streamlined body tapers at both ends so that the water closes smoothly behind it instead of forming eddies, which greatly reduces drag. That reduction is exactly why the shape has evolved in fish. Both are true and R explains A.