General Science GK Questions with Answers – Page 14

A monatomic element exists as single, separate atoms. Helium is a noble gas of group 18: its only shell, the first, is full with two electrons, so a helium atom has no tendency to share or transfer electrons and does not bond even with another helium atom.

Blood pressure is written as two numbers, and normal adult blood pressure is about 120/80 mm of mercury.

Anthropology, from the Greek 'anthropos' (human) and 'logos' (study), is the science of human beings: how societies and cultures began, how they changed and how people live today.

Adding hydrogen across the double or triple bond of an alkene or alkyne turns it into a saturated alkane; this reaction is called hydrogenation and it needs a catalyst.

Thyroxine is an animal hormone, made by the thyroid gland in the neck, and it controls the rate of metabolism in the human body.

In the Brønsted–Lowry theory an acid is any substance that gives away a proton, that is a hydrogen ion (H⁺), to another substance.

All three kinds of wave reflect, carry energy and exert pressure, but only electromagnetic waves can travel through a vacuum.

A kilogram-metre per second squared is mass times acceleration, which is force; it is the newton, not a unit of energy.

Coating iron or steel with a thin layer of zinc is called galvanisation, and it is the most common way to protect them from rusting.

Stretching the wire to twice its length makes its resistance four times larger, so at the same voltage the current falls to a quarter.

In his 1913 model of the atom, Bohr proposed that electrons move in certain fixed orbits, called stationary states, in which they do not radiate energy.

The field inside a long solenoid is directly proportional to the number of turns per unit length, so doubling n doubles the field.

A light year is the distance light travels in empty space in one year, so despite its name it measures length, not time.

The stretch of a spring is proportional to the force on it, and the weight of the mass on the Moon is one-sixth of its weight on Earth.

A primary rainbow comes from light that is refracted into a raindrop, reflected once inside it and refracted out again, and it is the brighter, inner bow.

Two trends of the periodic table decide the order. Going down a group, atomic radius increases because each new period adds an electron shell; so sodium, in period 3, is larger than lithium, in period 2, of the same group 1.

The endoplasmic reticulum (ER) is a network of membrane tubes and sacs inside the cell. Part of it is studded on the outside with tiny granules called ribosomes, which give it a dotted, rough look under an electron microscope; this part is the rough ER.

When an acid such as hydrochloric acid dissolves in water, it splits into ions: hydrogen ions (H⁺, which join water molecules as hydronium ions, H₃O⁺) and negative ions such as chloride (Cl⁻).

The power turned into heat in a wire carrying a current I is P = I²R, and the resistance of a wire is R = ρl/A, where ρ is the resistivity of its material.

A person with myopia sees nearby objects clearly but finds distant objects blurred, which is why the defect is called near-sightedness or short-sightedness.