Ans: (b)
193. Petroleum ether is also known as
     (a) kerosene
     (b) naphtha
     (c) lubricating oil
     (d) asphalt
Ans: (b)
194. Which one of the following is used for dry cleaning?
     (a) Kerosene oil
     (b) Diesel oil
     (c) Lubricating oil
     (d) Petroleum ether
Ans: (d)
195. Which of the following is used as an illuminant?
     (a) Gasoline
     (b) Benzoline
     (c) Kerosene
     (d) Petroleum ether
Ans: (c)
196. The alloy which is extremely hard and resistant to acids is
     (a) chrome steel
     (b) silicon steel
     (c) stainless steel
     (d) invar
Ans: (b)
197. The process of heating steel to bright red heat and cooling suddenly by plunging it into water is known as
     (a) annealing
     (b) hardening
     (c) quenching
     (d) tempering
Ans: (b)
198. Rusting of iron cannot be prevented by
     (a) painting
     (b) applying alkaline phosphate
     (c) applying soap water
     (d) galvanising
Ans: (c)
199. The percentage of silver in German silver is
     (a) ten
     (b) twenty
     (c) zero
     (d) fifty
Ans: (c)
200. Which of the following is a communicable disease caused by viruses?
     (a) Cholera
     (b) Dysentery
     (c) Diabetes
     (d) Measles