Chemical Engineering - Chemical Engineering Basics

21. 

What is the critical radius of insulation (cms) for a metallic cylinder, if the convective heat transfer co-efficient with the ambient atmosphere is 5 W/m2. °K ? Thermal conductivity of metal and insulation material are 40 and 0.1 W/m.°K respectively.

A. 2
B. 5
C. 10
D. 20

Answer: Option A

Explanation:

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22. 

Which set of materials is used as a moderator in nuclear reactor ?

A. Zircalloy & berrylium.
B. Zircalloy & heavy water.
C. Zirconium & berrylium.
D. Heavy water & berrelium.

Answer: Option D

Explanation:

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23. 

Malleabilisation heat treatment is performed on

A. cast steel
B. grey cast iron
C. white cast iron
D. spheroidal graphite cast iron

Answer: Option C

Explanation:

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24. 

For hardening high alloy steel, it is to be heated slowly and uniformly to avoid

A. local hardening
B. scale formation
C. segregation
D. warpage

Answer: Option D

Explanation:

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25. 

Disposable patterns are made of

A. metal
B. polystyrene
C. rubber
D. wood

Answer: Option B

Explanation:

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