156. A metal which exhibits allotropy is
     (a) cobalt
     (b) tin
     (c) manganese
     (d) platinum
Ans: (b)
157. The non-metal which is electropositive is
     (a) chlorine
     (b) nitrogen
     (c) sulphur
     (d) hydrogen
Ans: (d)
158. High temperature thermometers use
     (a) sodium amalgam
     (b) an alloy of sodium and potassium
     (c) silver amalgam
     (d) calcium amalgam
Ans: (b)
159. In the making of jewels, gold is usually mixed with
     (a) zinc
     (b) tin
     (c) copper
     (d) aluminium
Ans: (c)
160. Which of the following metals is the best conductor of heat and electricity?
     (a) Aluminium
     (b) Silver
     (c) Copper
     (d) Magnesium
Ans: (b)
161. Which of the following is an essential constituent of acids?
     (a) Oxygen
     (b) Nitrogen
     (c) Hydrogen
     (d) Chlorine
Ans: (c)
162. Calamine is a ore of
     (a) tine
     (b) magnesium
     (c) zinc
     (d) copper
Ans: (c)
163. The commonest ore of aluminium is
     (a) cryolite
     (b) bauxite
     (c) malachite
     (d) azurite
Ans: (b)