What is the product of $1, 4$-addition in the reaction shown below?

The dibromo compound $[P]$ (molecular formula : $C_{9}H_{10}Br_{2}$) when heated with excess sodamide followed by treatment with dilute $HCl$ gives $[Q]$. On warming $[Q]$ with mercuric sulphate and dilute sulphuric acid yields $[R]$ which gives positive Iodoform test but negative Tollen's test. The compound $[P]$ is:

Which alkene reacts fastest with $H_2$ under catalytic hydrogenation conditions?

What is the major product expected from the following reaction?

Identify the product $B$ in the following reaction sequence:
$1,4-\text{cyclohexadiene-1,4-dicarboxylic acid}$ $\xrightarrow{NaOH} A$ $\xrightarrow{\text{Kolbe electrolysis}} B$

Which of the following compounds gives a positive Baeyer's test but does not form a white precipitate with ammoniacal silver nitrate solution?