A             B          C        D
     (a)     4             2          3        1
     (b)     4             3          2        1
     (c)     1             2          3        4
     (d)     1             3          2        4
Ans: (b)
257. Which one of the following polymeric materials is used for making bullet proof jacket? [CDS 2009]
     (a) NYLON6, 6
     (b) RAYON
     (c) KEVLAR
     (d) DACRON
Ans: (c)
258. Which of the following statements about the commonly used automobile battery are true?
          I.         It is usually a lead-acid battery
         II.         It has six cells with a potential of 2 volt each.
        III.         Its cells work as Galvanic Cells while discharging power.
        IV.          Its cells work as electrolytic cells while recharging
     Select the correct answer using the code given below: [CDS 2009]
     (a)     I, II, III and IV
     (b)     I, II and III
     (c)     II and IV
     (d)     III and IV
Ans: (a)
259. The material used for electric fuse is an alloy of tin and lead. This alloy should have: [NDA 2011]
     (a) high specific resistance and low melting point
     (b) low specific resistance and high melting point
     (c) low specific resistance and low melting point
     (d) high specific resistance and high melting point
Ans: (a)
260. Which one among the following is the main ingredient in cement? [NDA 2011]
     (a) Gypsum
     (b) Lime stone
     (c) Clay
     (d) Ash
Ans: (b)
261. When concentrated H2SO4 splits on the surface, it should be immediately cleaned: [NDA 2011]
     (a) with a piece of cloth
     (b) by adding cold water
     (c) by adding solid Na2CO3
     (d) by adding solid BaCI2
Ans: (c)
262. When items of jewellery made of metals such as copper or nickel are placed in a solution having a salt of gold, a thin
     film of gold is deposited by [CDS 2011]
     (a) cooling to below 0°C