General Science GK Questions with Answers – Page 4

Zinc gives up electrons more readily than iron, so it corrodes first and keeps the iron safe. Coating iron or steel with a thin layer of zinc is called galvanisation.

An ECG records the electrical signals that make the heart muscle contract with each beat. Each heartbeat starts at the sino-atrial (SA) node, the natural pacemaker in the right atrium.

An echo is sound that bounces back from a hard surface such as a wall, cliff or hill and reaches our ears again.

Both stress and pressure are force per unit area, so both are measured in newton per square metre, or pascal (Pa).

A step-up transformer raises an alternating voltage, using more turns in its secondary coil than in its primary. A transformer works on electromagnetic induction and only with alternating current.

For an object between F and P, the image forms behind the mirror, not at infinity. When an object is placed between the pole and the principal focus of a concave mirror, the reflected rays spread out and never meet in front of the mirror.

Heat makes the copper wire expand a little, and a longer pendulum swings a little more slowly. The time period of a simple pendulum is T = 2π√(L/g), so it grows with the square root of the length.

This is the law of conservation of energy: energy only changes from one form to another. In any isolated system the total energy stays the same.

This reverses the truth: a voltmeter has a very high resistance and an ammeter a very low one. An ammeter measures the current flowing through a circuit, so it is placed in series and the whole current passes through it.

Movement of ions through protein channels is facilitated diffusion, a passive process that needs no energy from ATP. Active transport moves substances against their concentration gradient, from low to high concentration, using carrier proteins and energy, usually from ATP.

An emulsion is a colloid in which tiny droplets of one liquid are spread through another liquid with which it does not mix.

Both particles gain the same kinetic energy, but the electron is far lighter, so it ends up much faster. When a charge q is accelerated through a potential difference V, it gains kinetic energy equal to qV.

The object lies between F and 2F of the convex lens (25 cm and 50 cm), and such an object always gives a real, inverted and enlarged image beyond 2F. Using the lens formula 1/v − 1/u = 1/f with u = −40 cm and f = +25 cm gives…

Ribosomes are the only one of these found in prokaryotic cells such as bacteria, because they are not enclosed by a membrane.

Neither statement is correct: only starch is a mixture of amylose and amylopectin, and only glycogen is stored in liver cells.

Ultraviolet rays have the shortest wavelength of the three, visible light comes next and infrared rays have the longest. The electromagnetic spectrum, in order of increasing wavelength, runs from gamma rays and X-rays to ultraviolet, visible light, infrared, microwaves and radio waves.

The power of a lens measures how strongly it bends light, and +2.5 D has the largest magnitude among the four options.

Each of them is made of two simple sugar units joined together, which is exactly what a disaccharide is. Carbohydrates are grouped by the number of sugar units they contain.

Work is negative when the force acts opposite to the displacement, because the angle between them is then 180°. Work done is W = F S cos θ, where θ is the angle between the force and the displacement.

Once a satellite is placed in orbit with the right speed, the Earth's gravity keeps it going round without any engine.