Chemical Engineering - Chemical Engineering Basics

21. 

Which of the following metals can be extracted from its ore by both pyrometallur-gical as well as hydrometallurgical methods ?

A. Copper
B. Zinc
C. both 'a' & 'b'
D. neither 'a' nor 'b'

Answer: Option C

Explanation:

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22. 

If a heat transfer surface is pock-marked with a number of cavities, then as compared to a smooth surface the heat transfer by __________ will not increase.

A. convection
B. nucleate boiling
C. radiation
D. conduction

Answer: Option A

Explanation:

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23. 

Piezoelectric is a material

A. whose properties is midway between the constituent materials.
B. which gets polarised, when stressed.
C. in which magnetising force reduces when current flowing through it is in-cresed.
D. which changes dimensions due to applied field.

Answer: Option B

Explanation:

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24. 

Oxygen content below __________ percent in air contaminated with nitrogen does not support combustion and is unsafe for humane exposure.

A. 18
B. 16
C. 14
D. 12

Answer: Option B

Explanation:

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25. 

Moist air is cooled along the line of constant __________ , when it is passed over a cold & dry cooling coil, such that no condensation occurs.

A. enthalpy
B. relative humidity
C. wet bulb temperature
D. dew point temperature

Answer: Option D

Explanation:

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