51. Production of chlorofluorocarbons (CFC) gas which is proposed to be banned in India, is used in which of the following domestic products?
A. Television
B. Refrigerator
C. Tube light
D. Cooking gas
52. Balloons are filled with
A. nitrogen
B. helium
C. oxygen
D. argon
53. Which of the following does not contain a coinage metal?
A. Silver and Gold
B. Zinc and Gold
C. Copper and Silver
D. Copper and Gold
54. Which metal pollute the air of a big city?
A. Copper
B. Chromium
C. Lead
D. Cadmium
55. Bell metal is an alloy of
A. nickel and copper
B. zinc and copper
C. brass and nickel
D. tin and copper