140. Which or the following is not a constituent or gun powder?
     (a) Ammonium nitrate
     (b) Nitre
     (c) Charcoal powder
     (d) Sulphur
Ans: (a)
141. A non-metal which is a good conductor or heat and electricity is
     (a) iodine
     (b) sulphur
     (c) graphite
     (d) phosphorus
Ans: (c)
142. The earliest known acid is
     (a) nitric acid
     (b) oxalic acid
     (c) carbonic acid
     (d) acetic acid
Ans: (d)
143. The pH or pure water is nearly 7.0 It will increase on the addition or
     (a) hydrochloric acid
     (b) ammonia
     (c) cane sugar
     (d) common salt
Ans: (b)
144. Which or the following electrolysis?
     (a) Aluminium
     (b) Copper
     (c) Zinc
     (d) Iron
Ans: (a)
145. Cupellation is used in the purification of
     (a) Lead
     (b) Tin
     (c) Silver
     (d) Gold
Ans: (c)
146. Iron is coated with zinc to prevent rusting. The process is called
     (a) annealing
     (b) tempering
     (c) calcining
     (d) galvanising
Ans: (d)
147. Which one of the following metals is used to extract another metal?
     (a) Lead
     (b) Tin
     (c) Zinc
     (d) Aluminium
Ans: (d)