General Science Questions and Answers

Answer: C

Timing the interval between two sunsets - one seen lying down on the beach and the second after standing up - gives the radius of the earth.

Raising the eye by a known height lets you see a little further over the curve, and the extra delay before the sun sets again depends on how sharply the surface curves. The geometry then yields the earth's radius.

Answer: A

The adopted son is the one with O positive blood.

The parents are AB and O. An AB parent passes on either A or B, and an O parent passes on O, so every biological child must be group A or group B - never O and never AB. The son with group O therefore cannot be theirs.

Answer: A

A gas turning into a liquid is condensation.

The reverse, liquid to gas, is evaporation or boiling. A gas passing straight to a solid is deposition, and a solid straight to a gas is sublimation.

Answer: A

Earthquake magnitude is measured on the Richter scale, from the amplitude of the waves recorded on a seismograph.

It is logarithmic: each whole number is a tenfold rise in amplitude and about a thirtyfold rise in energy. The Mercalli scale, by contrast, rates the observed intensity of shaking rather than the energy released.

Answer: C

Night-vision equipment uses infrared. Every object above absolute zero emits infrared, and a warm body emits far more of it than its cool surroundings.

A thermal imager forms a picture from that emitted radiation, so it needs no light at all; image intensifiers instead amplify the faint visible and near-infrared light already present.

Answer: B

Your weight decreases slightly as you go down a well.

Below the surface, only the mass of the sphere beneath you pulls you inward - the shell above contributes nothing. Since that inner sphere is smaller, gravity weakens as you descend, reaching zero at the centre.

Answer: D

An object weighs least at the centre of the earth, where it weighs nothing at all.

There the mass of the earth surrounds it equally in every direction, so the pulls cancel exactly and \( g = 0 \). Weight is greatest at the poles, where the radius is smallest and there is no rotational effect.

Answer: D

All three - vitamin C, niacin and riboflavin - are water-soluble.

The water-soluble vitamins are C and the B group. They are not stored in the body to any extent, so a surplus is excreted in urine and a regular supply is needed. Vitamins A, D, E and K are fat-soluble and are stored in the liver.

Answer: C

Mudumalai National Park is in Tamil Nadu, in the Nilgiris district where the state meets Karnataka and Kerala.

It became India's first wildlife sanctuary in 1940 and was declared a tiger reserve in 2007. It adjoins Bandipur in Karnataka and Wayanad in Kerala.

Answer: C

The outermost layer of the sun is the corona, its tenuous outer atmosphere.

It extends millions of kilometres into space and is over a million degrees - far hotter than the 5,500°C photosphere beneath it, a discrepancy still not fully explained. Being faint, it is visible only during a total solar eclipse.