General Science Questions and Answers

Answer: C

The correct match is a-2, b-1, c-4, d-3.

• Linen is woven from fibres of the flax plant (2).
• Coir is the coarse fibre from the husk of the coconut (1).
• Mohair is the hair of the Angora goat (4).
• Down is the soft under-feathers of ducks and geese, used in quilts and jackets (3).

A common trap is to link mohair with the Angora rabbit; angora wool comes from the rabbit, but mohair comes from the Angora goat. The other codes swap linen and coir or misplace down.

Answer: C

It is the cryosphere.

The cryosphere (from the Greek kryos, cold) is the part of the Earth system where water is frozen: snow cover, glaciers, ice sheets, sea ice and floating ice, frozen ground and permafrost.

The biosphere is the zone of life. 'Greensphere' and 'Blusphere' are not terms for any part of the Earth system.

The other spheres of the Earth system are the lithosphere (rock), the hydrosphere (liquid water), the atmosphere (air) and the biosphere (life).

Answer: A

The indirect source is gravitation.

Information about the Earth's interior comes from direct sources, materials we can actually examine, and indirect sources, inferences from measurements. Variations in gravity at different places, together with magnetic surveys and seismic waves, are indirect sources.

Surface rocks, rocks obtained from mining and drilling, and material thrown out by volcanic eruptions can be examined directly, so they are direct sources.

Answer: A

The inner planet with no moons is Venus.

The inner (terrestrial) planets are Mercury, Venus, Earth and Mars. Mercury and Venus have no natural satellites.

Mars has two moons, Phobos and Deimos. Neptune is an outer planet with many moons, and Pluto is a dwarf planet beyond Neptune with five moons, so neither is an inner planet at all.

Earth has one moon, the only moon among the inner planets other than the two small moons of Mars.

Answer: A

The answer is (A) is true, but (R) is false.

The assertion follows the textbook classification: firewood and other biomass, together with fossil fuels such as coal, petroleum and natural gas, are the main conventional sources of energy, used on a large scale for a long time.

The reason is false. 'Conventional' means long and widely used, not renewable. Fossil fuels in particular are non-renewable, since they formed over millions of years and are being used up far faster than they form. Renewable sources such as solar and wind energy are usually grouped as non-conventional sources.

Answer: B

Only statement A is correct, so the answer is Only (A).

Planets have no light of their own. They shine because they reflect the light of a star, which in our solar system is the Sun, so statement A is true.

Statement B is false: Mercury, Venus, Earth and Mars are rocky, but Jupiter, Saturn, Uranus and Neptune are giant planets made largely of gases. Statement C is also false, because Mercury and Venus have no moons at all. Every option other than 'Only (A)' includes B or C, so each of them is wrong.

Answer: B

The reason is that it keeps people healthy.

Yoga combines postures, breathing exercises and meditation. Practised regularly it improves flexibility, strength, posture, breathing and circulation and helps reduce stress, so its main appeal worldwide, recognised in the International Day of Yoga, is the physical and mental health it brings.

Calling it simple exercise understates it, increased hunger is not its purpose, and happiness is at most one result of the overall health it promotes, not the general reason it is practised.

Answer: B

The keyed answer is both (A) and (R) are true and (R) is the correct explanation of (A).

(A) is true: solar and tidal energy are renewable sources because nature supplies them again and again. (R) is true: coal, petroleum and natural gas take thousands of years to form, so they cannot be renewed on a human timescale. The key reads (R) as the reason for the classification, since a source counts as renewable when it is replenished quickly, unlike those that need thousands of years.

Option 1 would treat (R) as true but not bearing on (A). Many readers would argue for that, since (R) describes non-renewable sources and not solar or tidal energy. Options 3 and 4 need a false statement, and neither statement is false.

Answer: A

(A) and (R) are both correct and (R) is the correct explanation for (A).

The Earth spins on its axis from west to east. To an observer on the rotating Earth, the sky therefore appears to turn the opposite way, so the stars, like the Sun and Moon, appear to rise in the east and move across the sky towards the west.

The apparent motion is a direct consequence of the Earth's rotation, so R is the reason for A. The stars' own motions are far too small to see in one night.

Answer: B

The incorrect statement is that air is not present in soil.

Soil contains air in the spaces between its particles. Pouring water on dry soil releases bubbles, which shows the air being pushed out. This air supplies oxygen to plant roots and to the earthworms, insects and microbes that live in the soil.

The other statements are correct: air has weight, which an inflated balloon on a balance shows; air occupies space, as an inverted glass pushed into water shows; and air plays an important role in the water cycle by carrying water vapour and by evaporation.