General Science GK Questions with Answers – Page 10

Among the options it is the only vitamin made by bacteria; no plant or animal cell can make it, so bacteria, including those in the gut, are its source.

Using v² = u² + 2as with u = 12 m/s, v = 0 and s = 45 m gives a = −144 ÷ 90 = −1.6 m/s².

The human brain has three main parts: the fore-brain, the mid-brain and the hind-brain. The hind-brain consists of the pons, the medulla and the cerebellum.

The mass of the solution is 20 g + 180 g = 200 g, and 20 g of salt in 200 g of solution is 10 per cent.

In a short circuit the resistance of the path falls almost to zero, so by Ohm's law the current rises sharply.

Cattle, buffaloes, goats and sheep are ruminants, and a ruminant's stomach has four chambers. The four chambers are the rumen, the reticulum, the omasum and the abomasum.

It reverses the facts: the pulmonary arteries carry deoxygenated blood and the pulmonary veins carry oxygenated blood. Arteries and veins are named by the direction of flow, not by the oxygen they carry.

This statement is false, because sound in air travels as longitudinal waves, not transverse waves. In a longitudinal wave, the particles of the medium vibrate back and forth along the direction in which the wave moves, forming compressions and rarefactions.

Power is the reciprocal of the focal length in metres, so P = 1 ÷ 0.25 m = +4 D. The power of a lens tells how strongly it converges or diverges light.

A solar cell turns the energy of sunlight directly into electricity through the photovoltaic effect. A solar cell is a large p-n junction, usually made of silicon.

With the same voltage, heat varies inversely as resistance, and the parallel resistance is one-fourth of the series resistance. The two wires are identical, so each has the same resistance R. In series the total resistance is R + R = 2R; in parallel it is R/2.

Tidal volume is the volume of air breathed in or out in one normal, quiet breath, about 500 mL in a healthy adult.

The cornea is a clear layer made of cells and proteins, chiefly collagen fibres laid out in a regular pattern that keeps it transparent.

The time period of a simple pendulum depends on its length but not on the mass of the bob, so halving the length divides the period by √2.

Potential difference is the work done per unit charge, so V = W/Q = 24 J ÷ 2 C = 12 V. The potential difference between two points is the work needed to move one coulomb of charge from one point to the other.

Pepsin works in the strongly acidic stomach, while trypsin works in the mildly alkaline small intestine. Pepsin is secreted by the chief cells of the stomach as inactive pepsinogen, which hydrochloric acid from the parietal cells turns into pepsin.

Kinetic energy equals p²/2m, so doubling the momentum p makes the kinetic energy four times as large. Momentum is p = mv and kinetic energy is KE = ½mv².

Mass by mass percentage is the mass of solute divided by the mass of the whole solution: 20 ÷ (20 + 180) × 100 = 10%.

Light keeps to a straight line only while its speed stays the same, which happens in a homogeneous, transparent medium.

. Cathode rays behave the same whatever gas is in the tube, so the statement that they depend on the gas is not correct.