General Science GK Questions with Answers – Page 17

Red light has the longest wavelength in the visible spectrum, so glass slows it the least and bends it the least.

For three equal resistors R in parallel, 1/Rp = 1/R + 1/R + 1/R = 3/R, so Rp = R/3.

The force needed equals the rate at which the belt must give horizontal momentum to the falling sand: F = v × (dm/dt) = 2 × 0.1 = 0.2 N. Newton's second law, in its general form, says force equals the rate of change of momentum.

The four terrestrial planets do lie between the Sun and the asteroid belt, but they are dense, not light, and their weak gravity could not hold on to escaping gases.

The Italian scientist Amedeo Avogadro proposed in 1811 that equal volumes of all gases, at the same temperature and pressure, hold the same number of molecules.

A plane mirror always forms an image that stands upright, cannot be caught on a screen, and has its left and right sides swapped.

A black hole forms when a very massive star collapses under its own gravity, and its pull becomes so strong that not even light can escape.

In uniform circular motion the speed stays the same, but the direction changes at every point, so the velocity keeps changing.

Antibodies are made by B-lymphocytes, a kind of white blood cell, after they meet a foreign antigen. When a germ or other foreign substance enters the body, B-lymphocytes that recognise its antigen multiply and turn into plasma cells.

Vitamin B1 is the chemical called thiamin (also spelt thiamine), the first of the B-complex vitamins to be identified. Thiamin is a water-soluble vitamin that helps the body turn carbohydrates into energy and keeps nerves and the heart working properly.

Colostrum is the thick, yellowish first milk a mother produces in the first few days after childbirth.

When a magnet moves inside a coil, the magnetic flux linked with the coil changes, and this change produces an electromotive force and a current.

Cooking soda, also called baking soda, is sodium hydrogen carbonate, also known as sodium bicarbonate. It is a mild base made from one sodium, one hydrogen, one carbon and three oxygen atoms.

The statement is wrong because the inner wall of a thermos flask is silvered so that it radiates very little heat; the shiny outer surface also reflects heat back rather than absorbing it.

Work equals force multiplied by displacement, and 4 N multiplied by 0.25 m gives exactly 1 joule.

In bacteria the DNA is not wrapped around histone proteins as it is in the chromosomes of eukaryotes, so it is called naked DNA.

Newton's law of cooling describes a hot body losing heat to cooler surroundings, which is exactly what a cup of coffee on a table does.

The two pathogens have been swapped: malaria is caused by Plasmodium and TB by Mycobacterium, so both pairs are wrong.

It is the heat a liquid absorbs to turn into vapour at its boiling point, while its temperature stays the same.

In every isolated system these three quantities stay constant, and no known process has ever been found to break these laws.