General Science Questions and Answers

Answer: C

The visible spectrum runs from about 3900 to 7600 angstrom - 390 to 760 nanometres.

Violet is at the short-wavelength end and red at the long. Below 390 nm is ultraviolet and above 760 nm infrared, neither of which the eye detects.

Answer: C

The decibel measures the loudness or intensity of sound.

It is logarithmic: 10 dB is a tenfold increase in intensity, so the scale can cover the enormous range the ear handles. Frequency, which determines pitch, is measured in hertz instead - cycles per second.

Answer: B

The Mid Day Meal scheme is the one aimed at school-going children, providing a cooked meal in government and aided schools.

Launched nationally in 1995, it is the largest school feeding programme in the world, and was intended to improve both nutrition and school attendance.

Answer: C

Epoxy resins are used as adhesives, and also as coatings and casting materials.

They are supplied as two parts - resin and hardener - that cross-link on mixing into a rigid solid, bonding strongly to metal, glass and ceramics.

Answer: C

A chronometer measures time - a clock accurate enough to keep time at sea.

John Harrison's marine chronometer, perfected in the 1760s, solved the longitude problem: comparing local noon with the time at a reference meridian gives longitude directly.

Answer: C

Isotopes are separated by fractional distillation, and by other methods that exploit the small difference their masses make - diffusion, centrifugation, electromagnetic separation.

Chemical methods cannot separate them, since isotopes of an element are chemically identical; only the mass differs, and the difference is largest for the lightest elements.

Answer: D

Radon is the radioactive pollutant found in building materials.

It is a gas produced by the decay of radium in stone, brick and concrete, and it seeps into buildings and collects in poorly ventilated rooms. It is the second commonest cause of lung cancer after smoking.

Answer: D

Air contains about 21 per cent oxygen by volume.

Nitrogen makes up about 78 per cent and argon 0.93 per cent, with carbon dioxide at about 0.04 per cent and traces of other gases.

Answer: D

None of these is a protein.

Natural rubber is a polymer of isoprene, and starch and cellulose are polymers of glucose - all three are made of carbon, hydrogen and oxygen only. A protein is a polymer of amino acids and must contain nitrogen.

Answer: C

Alpha particles have the least penetrating power - a sheet of paper or a few centimetres of air stops them.

They are heavy, doubly charged helium nuclei, so they interact strongly with matter and lose their energy quickly. That same property makes them extremely damaging if inhaled or swallowed.