Practice MCQ Questions and answers on General Science-GK

A nautical mile measures distance and a knot measures speed.

Knot is a unit of speed of ship.

"Light water" is the most commonly used moderator (roughly 75% of the world's reactors) although the term is slightly ambiguous, usually meaning natural fresh water, but could also refer to deuterium-depleted water.

Alpha ray is a positively charged particle emitted by a radioactive element.

Atoms are composed of Electrons and Nuclei.

In an atomic explosion, enormous energy is released which is due to the conversion of mass into energy. Since most of the mass of ordinary objects resides in protons and neutrons, converting all the energy of ordinary matter into more useful energy requires that the protons and neutrons be converted to lighter particles, or particles with no rest-mass at all. Based on Einstein's equation E = mc², the amount of energy added is relative to the mass gained by the proton multiplied by the speed of light squared. In other words, a lot of energy is converted into a relatively small amount of mass.

Isotopes are separated by Distillation.

The wavelength of x-ray is 1 angstrom.

Mesons are not produced by radioactive decay, but appear in nature only as short-lived products of very high-energy interactions in matter, between particles made of quarks. In cosmic ray interactions, for example, such particles are ordinary protons and neutrons. Mesons are hadronic subatomic particles composed of one quark and one anti-quark, bound together by the strong interaction. Because mesons are composed of sub-particles, they have a physical size, with a radius roughly one femtometre, which is about 2/3 the size of a proton or neutron. All mesons are unstable, with the longest-lived lasting for only a few hundredths of a microsecond. Charged mesons decay (sometimes through intermediate particles) to form electrons and neutrinos.

Thorium radioactive pollutant has recently drawn attention of public due to its occurrence in the building material.
Thorium is a naturally-occurring, slightly radioactive metal discovered in 1828 by the Swedish chemist Jons Jakob Berzelius, who named it after Thor, the Norse god of thunder. It is found in small amounts in most rocks and soils, where it is about three times more abundant than uranium.
The alpha particles can travel only very short distances through most materials and cannot go through human skin.