Materials and Construction

291. Platinum and silver are corroded by

1. Caustic soda solution
2. Phosphoric acid
3. Sulphuric acid (10%)
4. None of these

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292. Polymerisation reactor used for the production of styrene butadiene rubber (SBR) is made of

1. Cast iron
2. Stainless steel or glass lined vessel
3. Karbate
4. Wrought iron

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293. Polymerisation reactor used in the production of styrene butadiene rubber (SBR) is made of

1. Stainless steel or glass lined steel
2. Nickel clad steel
3. High silicon cast iron
4. Aluminium

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294. Polymorphism is not exhibited by

1. Carbon
2. Iron
3. Phosphorous
4. None of these

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295. Polythene (low or high density) containers are not corroded by

1. Sulphuric acid (10%) at room temperature
2. Nitric acid (95%) at room temperature
3. Sulphur trioxide at 60°C
4. Any of these

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296. Post weld heat treatment is done by

1. Normalising
2. Stress relieving
3. Tempering
4. Solution annealing

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297. Presence of 0.3 to 0.5% arsenic in copper increases its

1. Ductility
2. Malleability
3. Tenacity & hardness
4. Electrical conductivity

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298. Presence of cobalt in steel improves its

1. Cutting ability
2. Corrosion resistance
3. Tensile strength
4. None of these

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299. Presence of even 0.005% of _________ in copper makes it highly brittle, rendering it useless for wire-drawing.

1. Oxygen
2. Arsenic
3. Antimony
4. Bismuth

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300. Presence of even very minute amount (say 0.1%) of _________ in copper, reduces its electrical conductivity very seriously.

1. Bismuth
2. Arsenic
3. Antimony
4. Both (B) and (C)

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