Building Materials

401. Dry rot

1. Cracks the timber
2. Reduces the strength of timber
3. Reduces the timber to powder
4. Spoils the appearance of timber

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402. Pozzolana (or surkhi) is used in lime

1. To impart hydraulicity
2. To prevent shrinkage
3. To decrease the cost of construction
4. To decrease the setting time

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403. The size of modular bricks, is

1. 10 × 10 × 9 cm
2. 19 × 9 × 9 cm
3. 22.5 × 10 × 8.5 cm
4. 22.5 × 8.0 × 9 cm

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404. Plywood is obtained by gluing wooden sheets at

1. 100 to 150 N/cm²
2. 100 to 130°C
3. Both (A) and (B)
4. Neither (A) nor (B)

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405. The low voltage porcelain is mainly used for

1. Switch block
2. Insulating tubes
3. Lamp sockets
4. All of these

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406. The initial setting time of hydraulic lime, is

1. 30 minutes
2. 60 minutes
3. 90 minutes
4. 120 minutes

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407. PVC stands for

1. Plastic very compact
2. Polythene vinyl chloride
3. Polythene vinyl carbon
4. Polythene vanadium carbide

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408. Cement paints usually

1. Contain hydrated lime
2. Contain 5% to 10% colour pigments
3. Contain 5% sodium chloride
4. All the above

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409. The kiln which may work throughout the year, is

1. Clamp
2. Bull's kiln
3. Hoffman's kiln
4. None of these

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410. The main ingredient of a good quality brick earth, is

1. Magnesia
2. Lime
3. Silica
4. Alumina

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