General Science GK Questions with Answers – Page 115

Work done in moving a charge through a potential difference is W = Q × V, so W = 2 × 12 = 24 joule.

Use the third equation of motion, which links velocity and distance without needing time: v squared equals u squared plus 2as.

Power is the rate of doing work, so power equals work divided by time. Here the work is 120 J and the time is 3 seconds, which gives 120 divided by 3, that is 40 watts.

In humans the digestion of starch begins in the buccal cavity, that is the mouth. The salivary glands pour out about 1.5 litres of saliva a day, and the enzyme in it, salivary amylase or ptyalin, breaks starch into the simpler sugar maltose.

Fat is digested in the small intestine by these two secretions working together.

Red algae, the division Rhodophyta, live in water, mostly in warm and shallow sea water, with a few species in fresh water.

Both are tiny algae grown in tanks and sold as protein rich food supplements, and both have been studied as food for astronauts.

Gamma rays sit at the far end of the electromagnetic spectrum, with the shortest wavelength and therefore the highest frequency and energy.

The fusion of a male gamete with a female gamete is called fertilisation, and the single cell it produces is the zygote.

Guava is the classic jam fruit because it is rich in both pectin and acid, the two things a jam needs to set into a firm gel.

only. In a permanent magnet moving coil instrument the coil is pivoted in the field of a permanent magnet, so the deflecting torque is proportional to the current itself and not to its square.

When a floating body tilts a little, the centre of buoyancy shifts to the centre of the newly displaced water, and the vertical drawn through it cuts the original axis of the body at a point called the metacentre.

Lead and mercury are in fact the poorest conductors of heat among the metals, so calling them the best is wrong.

Epithelium covers the body and lines its organs, so it is the protective tissue. It forms the outer layer of the skin, the lining of the mouth, stomach, intestine, blood vessels and kidney tubules.

Silk comes from the cocoon spun by the caterpillar of a moth. The common silk moth is Bombyx mori, and rearing it is called sericulture.

Calaverite is gold telluride, with the formula AuTe2. It is one of the very few minerals in which gold occurs chemically combined rather than as the free metal, because gold is a noble metal that usually resists reaction.

Barium compounds such as barium nitrate give fireworks and signal flares a bright green flame. The colour comes from a flame test.

The ending 'al' marks an aldehyde, so propanal is the three-carbon aldehyde, CH3CH2CHO. An aldehyde carries the group -CHO at the end of the carbon chain, with the carbonyl carbon attached to a hydrogen.

This pair is wrong, because tomato contains oxalic acid, along with some citric and malic acid. Formic acid, or methanoic acid, is the acid of an ant sting and a bee sting, and its name comes from the Latin word for ant.

Urea is made industrially by reacting ammonia with carbon dioxide under high pressure. The process runs in two steps: ammonia and carbon dioxide first form ammonium carbamate, which then loses a water molecule to give urea.