(b) sugar
     (c) sulphur
     (d) common salt
Ans: (b)
149. Which of the following is the best conductor of electricity ?
     (a) Copper
     (b) Mica
     (c) Zinc
     (d) Silver
Ans: (d)
150. The main important feature of neutron bomb is that when it is dropped on a city, it would damage:
     (a) both the living organisms and buildings
     (b) the buildings but not the living organisms
     (c) the living organisms but spare buildings
     (d) None of the above
Ans: (c)
151. The age of most ancient geological formations is estimated by : [Teacher"s Exam 1994]
     (a) Potassium-argon method
     (b) Ra-Si method
     (c) C14 method
     (d) Uranium-lead method
Ans: (c)
152. The first synthetic fibre made by man was:
     (a) rayon
     (b) nylon
     (c) polyester
     (d) terrycott
Ans: (b)
153. Gypsum is added to cement clinker to :
     (a) increase the tensile strength of cement
     (b) bind the particles of calcium silicate
     (c) decrease the rate of setting of cement
     (d) facilitate the formation of colloidal gel
Ans: (c)
154. The rate of chemical reaction does not depend upon: [CRPF Exam 1990]
     (a) concentration
     (b) catalyst
     (c) temperature
     (d) pressure
Ans: (d)
155. Water is neither acidic nor alkaline because: [CDS 1995]
     (a) it cannot accept or donate protons
     (b) it boils at a high temperature
     (c) it can dissociate into equal number of hydrogen ions