For the reaction: $CH_2=CH-CH=CH_2 + HBr (1 \text{ eq}) \xrightarrow{80^{\circ}C} P_1 + P_2$ (where $P_1$ is the major product),identify $P_1$.

The product $(A)$ formed in the following reaction sequence is :
$CH_3-C \equiv CH$ $\rightarrow[(ii) HCN]{(i) Hg^{2+}, H_2SO_4}$ $\xrightarrow[(iii) H_2 / Ni]{} (A)$

Which of the following catalysts is used to convert an alkyne $(-C \equiv C-)$ to form a $cis$-alkene?

Consider compounds $A$, $B$, and $C$ with the following structural formulae:
$A = CH_3 - CH_2 - CH_2 - CH_2 - CH_2 - OH$
$B = CH_2 = CH - CH_2 - CH_2 - CH_3$
$C = HO - CH_2 - CH_2 - CH(OH) - CH_3$
For the conversion of $B$ from $A$, the reagent $(D)$ required is . . . . . . and the structural formula of the product $(E)$ obtained when $C$ undergoes the same reaction using excess reagent $(D)$ is . . . . . . .

Which of the following alkenes can generate optically active compounds upon hydrogenation?

Which reaction has the lowest $\Delta G^{\ddagger}$ (Activation Energy)?