General Science GK Questions with Answers – Page 30

The acid-secreting cells of the stomach, called oxyntic or parietal cells, release hydrochloric acid, which protein digestion in the stomach depends on.

The body falls freely from rest through 50 m, so v² = 2gh = 2 × 9.8 × 50 = 980, giving v = √980, about 31.3 m s⁻¹; its total energy at release is all potential energy, mgh = 2 × 9.8 × 50 = 980 J. Because the…

Almost all the mass of an atom is in its nucleus, so the mass number, which the question calls atomic mass, is the total of protons and neutrons, the two kinds of nucleons.

This is the defining condition of simple harmonic motion, written F = −kx, where k is the force constant and the minus sign shows that the force always points back towards the mean position.

Using the lens formula with sign conventions, the object is found to be 10 cm from the lens, and the magnification v/u comes to 0.5.

In the rock-salt structure of sodium chloride, every Na+ ion is surrounded by six Cl− ions and every Cl− ion by six Na+ ions, so the coordination number is 6 for both.

The statement is false because CaSO4·2H2O is gypsum; Plaster of Paris is calcium sulphate hemihydrate, CaSO4·½H2O. When gypsum is heated to about 373 K, it loses three-quarters of its water and becomes Plaster of Paris, a white powder.

Tidal volume, the air breathed in or out in one normal quiet breath, is only about 500 millilitres in a healthy adult, the smallest of the four volumes listed.

Frogs and most fishes release their eggs and sperm into water, where fertilisation takes place outside the female's body. In external fertilisation, a large number of eggs and sperm are shed together, because many are lost to currents and predators.

The Geiger-Müller counter detects and counts the ionising radiation given out by radioactive substances, so it is the standard instrument for measuring radioactivity.

Muscle cells are packed with the contractile proteins actin and myosin, whose filaments slide over each other to shorten the cell and produce movement.

Ultrasound is sound with a frequency above 20,000 hertz, the upper limit of human hearing, so its defining feature is a higher frequency than audible sound.

The atomic number, the number of protons in the nucleus, decides which element an atom is, and no two elements share it.

The frequency of a wave is set by its source, so it does not change when light passes from air into glass; only the speed and wavelength change.

Since both wires have the same material and thickness, resistance is proportional to length, so R2 = 2R1, and the parallel combination works out to R = 2R1/3.

With uniform acceleration, velocity changes by the same amount in every equal interval of time, so the velocity-time graph is a straight line whose slope equals the acceleration.

The statement is false because the latent heat of fusion of ice is high, about 334 joules per gram, or roughly 80 calories per gram.

Lime water is a clear solution of calcium hydroxide, and carbon dioxide reacts with it to form insoluble calcium carbonate, which turns the solution milky.

The nucellus is the mass of tissue inside the ovule whose cells carry stored food, and the embryo sac develops within it.

The corpus callosum is a thick band of nerve fibres that joins the two cerebral hemispheres, so it belongs to the forebrain, not the hindbrain.