Friday, April 26, 2019

WBCS Polity and Constitution MCQs Prelims and Mains

WBCS Previous Years MCQs on General Science (Chemistry) P5



41. Artificial rain is caused by spraying small pellets of which of the following over clouds?
(A) NaOH
(B) NH4Cl
(C) Ice
(D) Dry ice.

Correct Answer: [D] Dry ice.

42. The term PVC used in the plastic industry stands for
(A) Poly Vinyl Chloride
(B) Phospho Vanadium Chloride
(C) Phospho Vinyl Chloride
(D) Poly Vinyl Carbonate.

Correct Answer: [A] Poly Vinyl Chloride.

43. Which among the following is responsible for the depletion of the Ozone layer?
(A) Chlorofluorocarbon
(B) Mercuric oxide
(C) Carbon monoxide
(D) Carbon dioxide.

Correct Answer: [A] Chlorofluorocarbon.

44. Aluminium powder mixed with linseed oil is used as
(A) Insecticide
(B) Explosive
(C) Paint
(D) Fertilizer.

Correct Answer: [C] Paint.

45. The half-life period of an isotope is 2 hours. After 6 hours what fraction of the initial quantity of the isotope will be left behind?
(A) 1/8
(B) 1/4
(C) 1/6
(D) 1/3.

Correct Answer: [A] 1/8.




46. Nuclei of radioactive elements emit
(A) Either protons or neutrons
(B) Neither protons nor neutrons
(C) Neutrons
(D) Protons.

Correct Answer: [B] Neither protons nor neutrons.

47. L.P.G. Cylinders contain inside
(A) Isobutane and Propane
(B) Butane, Isobutane, and Propane
(C) Butane and Isobutane
(D) Butane and Propane.

Correct Answer: [B] Butane, Isobutane, and Propane.

48. Which one of the following is an element?
(A) Graphite
(B) Glass
(C) Table salt
(D) Water.

Correct Answer: [A] Graphite.

49. At constant temperature, if the pressure decrease, then the volume of a given mass of gas will
(A) Remain constant
(B) May increase or decrease depending on the nature of the gas
(C) Increase
(D) Decrease.

Correct Answer: [C] Increase.

50. Which of the following is physical change?
(A) Magnetizing a needle
(B) Rusting of iron
(C) Radioactive decay
(D) Photosynthesis.

Correct Answer: [A] Magnetising a needle.



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