Identify the alkyne formed by the reaction of calcium carbide with water.

When acetylene is passed through dilute $H_2SO_4$ in the presence of $HgSO_4$,the compound formed is .....

Which of the following gases is used for welding?

The synthesis of $3$-octyne is achieved by adding a mixture of sodium amide and an alkyne to a bromoalkane. What are these bromoalkane and alkyne?

The number of possible alkynes with the molecular formula $C_5H_8$ is

The reagent$(s)$ for the following conversion is/are:
$Br-CH_2-CH_2-Br \xrightarrow{?} HC \equiv CH$