16.
The inert gas which is substituted for nitrogen in the air used by deep sea divers for breathing, is
A. Argon B. Xenon
C. Helium D. Krypton
Answer & Explanation
Answer: Option C
Explanation:
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17.
The gases used in different types of welding would include
A. oxygen and hydrogen
B. oxygen, hydrogen, acetylene and nitrogen
C. oxygen, acetylene and argon
D. oxygen and acetylene
Answer & Explanation
Answer: Option D
Explanation:
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18.
The property of a substance to absorb moisture from the air on exposure is called
A. osmosis B. deliquescence
C. efflorescence D. desiccation
Answer & Explanation
Answer: Option B
Explanation:
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19.
In which of the following activities silicon carbide is used?
A. Making cement and glass
B. Disinfecting water of ponds
C. cutting very hard substances
D. Making casts for statues
Answer & Explanation
Answer: Option C
Explanation:
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20.
The average salinity of sea water is
A. 3% B. 3.5%
C. 2.5% D. 2%
Answer & Explanation
Answer: Option B
Explanation:
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