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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