Question

Oxyacetylene flame is used in/for:
A. Illumination
B. Welding
C. Hydrogenation
D. None of the above

Answer 1

Hint: It is suitable for repairing and construction works. Also, the chemical reaction between acetylene and oxygen is exothermic in nature.

Complete step by step solution:
We already know that the IUPAC name of acetylene gas is ethyne and its chemical formula is $\mathop C\nolimits_2 \mathop H\nolimits_2 $. It is colorless and inflammable gas. It is also called fuel gas and is used in combination with oxygen for generating high temperatures.
When acetylene is burned with oxygen, then it gets decomposed into its constituent elements namely carbon and hydrogen and releases a great amount of heat which can ignite the gas even in the absence of air or oxygen.
As there is a release of a large amount of heat and a very high temperature flame is produced, oxyacetylene flame is used for the purpose of welding.
Oxyacetylene welding is also known as oxy-fuel welding, oxy welding or gas welding. Three different types of flame are used in oxyacetylene welding namely, neutral (Ratio of oxygen and acetylene is 1:1), carburizing (excess acetylene) and oxidizing (excess oxygen).
Hence, on the above decision, we can say that option B is the correct answer.

Additional information:
Oxyacetylene welding has a slow rate of heating.
This wielding is not suitable for reactive metals.
Also, it has been seen that there is a lot of problem in handling and storage of acetylene gas.

Note: We have to take special care that we should always close the oxygen valve first whenever an oxy acetylene system is turned off.
Also, it is known that oxy acetylene produces very high temperature flame of about $3000^\circ$C.