Ans: (b)
172. Give the increasing order of the atomic masses of the following elements :
          1) Hydrogen
          2) Oxygen
          3) Helium
          4) Carbon
     (a) 1, 2, 3, 4
     (b) 4, 3, 2, 1
     (c) 2, 3, 1, 4
     (d) 1, 3, 4, 2
Ans: (d)
173. Match the following:
     A. Natural gas           1. Protein found in the outer layer of the human skin
     B. Mustard gas           2. Solid carbon dioxide
     C. Keratin               3. Poisonous liquid used in chemical warfare
     D. Dry ice               4. A mixture of gases occurring in pockets below the earth"s surface
          A          B        C         D
     (a)  3          2        1         4
     (b)  2          3        4         1
     (c)  4          3        1         2
     (d)  1          2        3         4
Ans: (c)
174. What is the main constituent of natural gas? [NDA 2004]
     (a) Methane
     (b) Ethane
     (c) Butane
     (d) Hydrogen
Ans: (a)
175. "IC chips" for computers are usually made of:
     (a) lead
     (b) chromium
     (c) silicon
     (d) gold
Ans: (c)
176. What is laughing gas? [RRB 1993]
     (a) Carbon dioxide
     (b) Sulphur dioxide
     (c) Hydrogen peroxide
     (d) Nitrous oxide
Ans: (d)
177. Chlorophyll is a naturally occurring chelate compound in which the central metal is : [IAS 1992]
     (a) iron
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