General Science Questions and Answers

Answer: A

Fuse wire is made of an alloy of tin and lead.

The alloy has a low melting point, so the wire parts before the circuit behind it can overheat, and a high resistivity, so it becomes the hottest point in the circuit for a given current.

Answer: C

The Nobel Prize was first awarded in 1901, five years after Alfred Nobel's death, under the terms of his will.

The original prizes were for physics, chemistry, medicine, literature and peace; the economics prize was added by the Swedish central bank in 1969.

Answer: A

Light is far faster than sound - 3 × 10⁸ m/s in vacuum against about 340 m/s for sound in air, roughly 900,000 times faster.

This is why lightning is seen before the thunder is heard, and why counting the seconds between them gives the distance of the storm at about 3 seconds per kilometre.

Answer: A

Tides are caused chiefly by the gravitational attraction of the moon, with the sun contributing about half as much.

The moon pulls the water nearest it into a bulge, and the water on the far side is left behind in a second bulge, so most coasts have two high tides a day.

Answer: C

The ozone layer blocks ultraviolet radiation.

It absorbs essentially all UV-C and about 90 per cent of UV-B, which would otherwise cause skin cancer and cataracts and damage crops and plankton. Infrared and radio waves pass through it freely.

Answer: B

The amount of water vapour in the air is its humidity.

Relative humidity, the figure usually quoted, is the vapour present as a percentage of the maximum the air could hold at that temperature. Warm air holds far more, which is why cooling air to its dew point produces dew, mist or rain.

Answer: D

Glass is made from sand and silicates - silica fused with sodium carbonate and limestone.

The soda lowers silica's melting point from about 1,700°C to a workable temperature, and the lime stops the product dissolving in water. The mixture cools to a rigid but non-crystalline solid.

Answer: A

Three-dimensional photographs made with laser light are holograms.

A hologram records the interference pattern between light reflected from the object and a reference beam, so it stores the phase of the light as well as its intensity. Illuminating the record reconstructs the wavefront, and the image shifts as the viewer moves, as a real object would.

Answer: A

Entomology is the study of insects, from the Greek entomon, insect.

Insects are the largest class of animals, with about a million described species. Ornithology covers birds, ichthyology fish and petrology rocks.

Answer: C

Ecology is the study of organisms in relation to their environment and to one another.

The word was coined by Ernst Haeckel in 1866 from the Greek oikos, household. It covers populations, communities and ecosystems, and the flow of energy and cycling of matter through them.