91. Which one of the following is used to measure the rate of nuclear disintegration?

(a) Geiger-Muller counter
(b) Cyclotron
(c) NMR spectroscopy
(d) Mass spectrograph

Answer: (a)

92. Which one of the following furnaces is used to reduce iron ore to pig- iron?
(a) Puddling furnace
(b) Open-hearth furnace
(c) Blast furnace
(d) Reheating furnace

Answer: (c)

93. Which one of the following furnaces separates the material from the hot gases during metallurgy?
(a) Blast furnace
(b) Retort furnace
(c) Reverberatory furnace
(d) Open-hearth furnace

Answer: (c)

94. Specific heating capacity of a furnace is expressed as
(a) Weight heated / hr / furnace area
(b) Weight heated / furnace volume
(c) Weight heated / hr / furnace volume
(d) Furnace area / Weight heated

Answer: (c)

95. Heruth furnace is an electric furnace for manufacture of very fine steel. Which of the following statements are correct?
1. It has a steel shell lined inside with basic lining of dolomite or magnesite
2. It has movable water-jacketed electrodes
3. The charge consists of scrap steel, cast iron and iron ore
4. The steel obtained is free from S but there are few gas bubbles

(a) 1, 2 and 4
(b) 1, 3 and 4
(c) 2, 3 and 4
(d) 1, 2 and 3

Answer: (d)

96. Buna – S is a co-polymer of
(a) Butadiene and acrylonitrile
(b) Butadiene and ethylene
(c) Vinyl chloride and vinyl alcohol
(d) Butadiene and styrene

Answer: (d)

97. Which of the following are condensation polymers?
1. Teflon
2. Dacron
3. Nylon
4. Bakelite

(a) 2, 3 and 4
(b) 1, 2 and 3
(c) 1, 2 and 4
(d) 1, 3 and 4

Answer: (a)

98. Which one of the following corrosions occurs when two dissimilar metals are in electrical contact with each other and exposed to electrolyte?
(a) Galvanic corrosion
(b) Oxidation corrosion
(c) Inter granular corrosion
(d) Liquid metal corrosion

Answer: (a)

99. Which one of the following corrosion occurs due to concentration difference in a component?
(a) Uniform
(b) Galvanic
(c) Inter-granular
(d) Exfoliation

Answer: (c)

100. Corrosion which is limited to extremely narrow zone adjacent to the weld is known as:
(a) Pitting corrosion
(b) Knife-line attack
(c) Stress corrosion
(d) Crevice attack

Answer: (b)