Which of the following has the highest heat of hydrogenation?

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:

$2CH_3-C(Ph)=CH_2 \xrightarrow{H-A (acid)} (A) (major)$
Product $(A)$ is:

Which type of reactions are easily performed by alkane and alkene?

The main product of the following reaction is:

The following reaction takes place in high yields. Use your knowledge of alkene chemistry to predict the product.