Ans: (b)
127. Which of the following is the lightest metal? [Bank PO 1991]
     (a) Mercury
     (b) Silver
     (c) Lithium
     (d) Lead
Ans: (c)
128. The charcoal used to decolourise raw sugar is:
     (a) animal charcoal
     (b) sugar charcoal
     (c) coconut charcoal
     (d) wood charcoal
Ans: (d)
129. The gas used to extinguish fire is :
     (a) neon
     (b) nitrogen
     (c) carbon dioxide
     (d) carbon monoxide
Ans: (c)
130. The element common to all acids is : [CDS 1987]
     (a) carbon
     (b) hydrogen
     (c) oxygen
     (d) sulphur
Ans: (b)
131. The most important ore of aluminium is : [RRB1991]
     (a) bauxite
     (b) calamine
     (c) calcite
     (d) galena
Ans: (a)
132. Stainless steel is an alloy of:
     (a) iron, carbon and nickel
     (b) iron and manganese
     (c) iron, chromium and zinc
     (d) iron, chromium and nickel
Ans: (d)
133. Which form of phosphorus is used in safety matches?
     (a) White phosphorus
     (b) Yellow phosphorus
     (c) Red phosphorus
     (d) Black phosphorus
Ans: (c)
134. Which of the following is used as a material for making protective windows in space probes?
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