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GENERAL SCIENCE MCQs

Total Questions : 67 | Page 5 of 7 pages
Question 41. Knot is a unit of speed of which of the following?
  1.    Aeroplane
  2.    Light waves
  3.    Ship
  4.    Sound waves
 Discuss Question
Answer: Option C. -> Ship
Knot is a unit of speed of ship.
Question 42. Which of the following is used as a moderator in nuclear reactor?
  1.    Thorium
  2.    Graphite
  3.    Radium
  4.    Ordinary water
 Discuss Question
Answer: Option D. -> Ordinary water
"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.
Question 43. In an atomic explosion, enormous energy is released which is due to
  1.    Conversion of chemical energy into heat energy
  2.    Conversion of mechanical energy into nuclear energy
  3.    Conversion of mass into energy
  4.    Conversion of neutrons into protons
 Discuss Question
Answer: Option C. -> Conversion of mass into energy
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.
Question 44. Isotopes are separated by:
  1.    Crystallisation
  2.    Sublimation
  3.    Distillation
  4.    Filtration
 Discuss Question
Answer: Option C. -> Distillation
Isotopes are separated by Distillation.
Question 45. The wavelength of X-rays is of the order of
  1.    10 micron
  2.    1 angstrom
  3.    1 cm
  4.    1 m
 Discuss Question
Answer: Option B. -> 1 angstrom
The wavelength of x-ray is 1 angstrom.
Question 46. Which radioactive pollutant has recently drawn to public, due to its occurrence in the building material?
  1.    Thorium
  2.    Radium
  3.    Plutonium
  4.    Radan
 Discuss Question
Answer: Option A. -> Thorium
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.
Question 47. Mesons are found in
  1.    Laser beam
  2.    X-rays
  3.    Gamma rays
  4.    Cosmic rays
 Discuss Question
Answer: Option D. -> Cosmic rays
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.
Question 48. In vulcanisation, natural rubber is heated with
  1.    Carbon
  2.    Silicon
  3.    Sulphur
  4.    Phosphorous
 Discuss Question
Answer: Option C. -> Sulphur
Vulcanization is a chemical process in which the rubber is heated with sulphur, accelerator and activator at 140–160°C. The process involves the formation of cross-links between long rubber molecules so as to achieve improved elasticity, resilience, tensile strength, viscosity, hardness and weather resistance.
Question 49. Deep blue colour is imparted to glass by the presence of
  1.    Cupric oxide
  2.    Nickel oxide
  3.    Cobalt oxide
  4.    Iron oxide
 Discuss Question
Answer: Option C. -> Cobalt oxide
Cobalt is a very intense glass colorant and very little is required to show a noticeable amount of colour. Colour of Cobalt glass is blue.
Question 50. What are the soaps?
  1.    Salts of silicates
  2.    Mixture of glycerol and alcohols
  3.    Sodium or potassium salts of heavier fatty acids
  4.    Esters of heavy fatty acids
 Discuss Question
Answer: Option C. -> Sodium or potassium salts of heavier fatty acids
Soap is a salt of a fatty acid used in a variety of cleansing and lubricating products. In a domestic setting, soaps are surfactants usually used for washing, bathing, and other types of housekeeping. In industrial settings, soaps are used as thickeners, components of some lubricants, and precursors to catalysts.

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