288. ________ is left behind after distillation of petroleum.
     (a) Arsenic
     (b) Barium
     (c) Benzene
     (d) Bitumen
Ans: (d)
289. Which of the following represents a physical change?
     (a) sublimation
     (b) oxidation
     (c) reduction
     (d) decomposition
Ans: (a)
290. Dry Ice is
     (a) solid carbon dioxide
     (b) liquid oxygen
     (c) liquid hydrogen
     (d) liquid. Chlorine
Ans: (a)
291. Hydrogen gas has
     (a) a very sweet smell
     (b) a very pungent smell
     (c) an irritating smell
     (d) no smell at all
Ans: (d)
292. Galvanised iron sheets are protected from rusting due to the presence of a layer of
     (a) lead
     (b) chromium
     (c) zinc
     (d) tin
Ans: (c)
293. Which one of the following elements is alloyed with iron to produce steel which can resist high temperatures and
     also have high hardness and abrasion resistance?
     (a) Aluminium
     (b) Chromium
     (c) Nickel
     (d) Tungsten
Ans: (b)
294. Oxalic acid is used in the manufacture of
     (a) tincture iodine
     (b) paints
     (c) ink
     (d) aerated water
Ans: (c)
295. Ozone is an allotrope of Oxygen, containing ______ atom/s of oxygen per molecule instead of two.
     (a) three
     (b) four
     (c) one
     (d) five