Acetone can be converted into pinacol by:

An ester $(A)$ with molecular formula $C_9H_{10}O_2$ was treated with excess of $CH_3MgBr$ and the complex so formed was treated with $H_2SO_4$ to give an olefin $(B)$. Ozonolysis of $(B)$ gave a ketone with molecular formula $C_8H_8O$ which shows positive iodoform test. The structure of $(A)$ is

Benzene on reaction with acetyl chloride in the presence of anhydrous $AlCl_3$ gave the product $P$. The product $P$ on reaction with methyl magnesium bromide followed by treatment with water furnished the product $Q$. The molecular formula of $Q$ is

The major product of the following reaction is

When $(X)$ reacts with $(Y)$ in the presence of dilute $(Z)$ solution,$3-$hydroxybutanal is formed. What are $(X), (Y),$ and $(Z)$?

Propyne was subjected to a reaction with $HgSO_4/dil. H_2SO_4$,which resulted in a product $P$. The product $P$ was heated with $Ba(OH)_2$ to give the product $Q$. The molecular formula of the product $Q$ is