16.

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 and Explanation
Answer:D
Explanation: No answer description available for this question.
17.

The property of a substance to absorb moisture from the air on exposure is called
A. osmosis B. deliquescence
C. efflorescence D. desiccation
Answer and Explanation
Answer:B
Explanation: No answer description available for this question.
18.

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 and Explanation
Answer:C
Explanation: No answer description available for this question.
19.

When an iron nail gets rusted, iron oxide is formed
A. without any change in the weight of the nail B. with decrease in the weight of the nail
C. with increase in the weight of the nail D. without any change in colour or weight of the nail
Answer and Explanation
Answer:C
Explanation: No answer description available for this question.
20.

The average salinity of sea water is
A. 3% B. 3.5%
C. 2.5% D. 2%
Answer and Explanation
Answer:B
Explanation: No answer description available for this question.