Materials and Construction

471. Which one occupies the lowermost position in the electromotive series of metals?

1. Aluminium
2. Noble metals (Ag, Pt, Au)
3. Zinc
4. Alkali metals (K, Na, Li)

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472. White cast iron as compared to grey cast iron is

1. More durable
2. Very brittle
3. Very hard
4. All (A), (B) & (C)

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473. White cast iron is not

1. Malleable
2. Whitish in color
3. Brittle
4. Strong and hard

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474. White metal is an alloy of

1. Lead, tin and cadmium
2. Copper, tin and zinc
3. Copper and lead
4. None of these

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475. With increase in carbide/graphite ratio in cast iron, its

1. Hardness & brittleness increases
2. Ductility decreases
3. Both (A) and (B)
4. Neither (A) nor (B)

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476. With increase in the carbon percentage in the steel, its

1. Hardness increases
2. Ductility reduces
3. Tensile strength increases
4. All (A), (B) and (C)

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477. Wood is corroded by

1. Hydrochloric acid
2. SO2 (dry or wet)
3. Chlorine (dry or wet)
4. All (A), (B) and (C)

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478. Wood metal is not used for making

1. Soft solder
2. Casting for dental work
3. Storage tank for storing brine and caustic soda
4. Fusible safety plug for pressure cooker

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479. Work hardening of a material

1. Decreases its tensile strength
2. Decreases its ductility
3. Increases its ductility
4. Does not affect its ductility

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480. Wrought iron is

1. High carbon iron
2. Highly resistance to acid corrosion
3. Malleable & ductile; and hence is used for chain links, hooks & couplings
4. An alloy of iron, chromium & carbon

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