(d) Limestone and clay
Ans: (d)
50. Which synthetic fibre is known as artificial silk?
    (a) Cotton
    (b) Rayon
    (c) Terylene
    (d) Nylon
Ans: (b)
51. The major ingredient of leather is : [IAS 1988]
    (a) carbohydrate
    (b) collagen
    (c) polymer
    (d) nucleic acid
Ans: (b)
52. In the manufacturing of safety matches, which of the following materials are used to coat the two sides of match boxes?
    [NDA 1992]
         1) Yellow phosphorus
         2) 2.Glue
         3) Glass powder
         4) Red phosphorus
    (a) 1, 2 and 3
    (b) 1, 3 and 4
    (c) 1, 2 and 4
    (d) 2, 3 and 4
Ans: (c)
53. Glass is made of the mixture of: [LIC 1993]
    (a) quartz and mica
    (b) sand and salt
    (c) sand and silicates
    (d) None of the above
Ans: (c)
54. Which of the following are true regarding a catalyst? [CDS 1992]
    Wrong Question
         1) It is a substance which increases the rate of reaction.
         2) It is a substance which reduces the activation energy.
         3) It is substance which is consumed in the reaction.
    (a)  1 and 2
    (b)  2 and 3
    (c)  3 and 4
    (d)  1 and 4
Ans: (a)
55. The chemical used as a "fixer" in photography is : [IAS 1995]
    (a) borax
    (b) sodium thiosulphate
    (c) sodium sulphate