What is formed when calcium carbide reacts with heavy water?

Which combination is best for the preparation of the compound $(A)$ shown below?

Give the method of preparation of ethyne (acetylene) from vicinal dihalides.

Which of the following organic compounds has the same hybridization as its combustion product $(CO_2)$?

When acetylene is passed through a solution of dilute sulfuric acid containing mercuric sulfate,the number of $\pi$ bonds in the final product obtained is.........

What are $X$ and $Y$ respectively in the following reactions?
$X + 2D_2O \rightarrow C_2D_2 + P$
$Y + 12D_2O \rightarrow 3CD_4 + Q$