141. Non-stick cooking utensils are coated with: [I. Tax Central Excise 1993]
     (a) black paint
     (b) PVC
     (c) teflon
     (d) Polystyrene
Ans: (c)
142. Permanent hardness of water can be removed by adding: [NDA 1991]
     (a) potassium permanganate
     (b) chlorine
     (c) bleaching powder
     (d) washing soda
Ans: (d)
143. Which of the following is not correctly matched? [NDA 1993]
     (a) Galena: Lead sulphide
     (b) Green vitriol: Copper sulphate
     (c) Plaster of Paris: Calcium sulphate
     (d) Calomel: Mercurous chloride
Ans: (b)
144. The formula of plaster of paris is:
     (a) CaSO2
     (b) CaSO4 . 2H2O
     (c) 2CaSO4 . 4H2O
     (d) 2CaSO4 . H2O
Ans: (d)
145. Which of the following substances is a bad conductor of electricity but a good conductor of heat? [RRB1993]
     (a) Asbestos
     (b) Celluloid
     (c) Purspecks
     (d) Mica
Ans: (d)
146. Which of the following pairs does not contain a coinage metal? [CDS 1990]
     (a) Copper and Gold
     (b) Silver and Gold
     (c) Zinc and Gold
     (d) Copper and Silver
Ans: (c)
147. Which of following is an element? [IAS 1992]
     (a) Ruby
     (b) Sapphire
     (c) Emerald
     (d) Diamond
Ans: (d)
148. Most soluble in water is :
     (a) camphor