The number of $\sigma$ and $\pi$ bonds between two carbon atoms in calcium carbide are

Write structures of different isomers corresponding to the $5^{th}$ member of alkyne series. Also write $IUPAC$ names of all the isomers. What type of isomerism is exhibited by different pairs of isomers?

$CH \equiv CH + HBr \to X$,the product $X$ is:

Which of the following is Lindlar catalyst?

Explain the acidic nature of ethyne.

$CH \equiv CH + CO + H_2O \xrightarrow{Ni(CO)_4} \text{Product}$. For this reaction,which statement is false?