Propylene on hydrolysis with sulphuric acid forms

The $IUPAC$ names of some alkenes are given below. Determine the correct stability order: $A$. $2$-Methylbut-$2$-ene, $B$. $cis$-But-$2$-ene, $C$. $2,3$-Dimethylbut-$2$-ene, $D$. Prop-$1$-ene.

$I$. $(CH_3)_2 C=CH_2 \xrightarrow{KMnO_4 / H^{+}} X + CO_2 + H_2 O$
$II$. $CH_3-CH=CH-CH_3 \xrightarrow{KMnO_4 / H^{+}} Y$
The functional groups in $X$ and $Y$ are respectively

Consider the following reactions:
$Ph-CH_2-CH=CH_2 \xrightarrow{H^+/H_2O} P$
$Ph-CH_2-CH=CH_2 \xrightarrow[(ii) NaBD_4]{(i) Hg(OAc)_2, H_2O} Q$
$Ph-CH_2-CH=CH_2 \xrightarrow[(ii) H_2O_2/OH^-]{(i) BD_3, THF} R$
Identify the products $P, Q$ and $R$.

What is the correct order of reactivity of alkenes towards acid-catalyzed hydration to form alcohols?

$CH_3-CH=CH_2$ $\xrightarrow{Br_2, hv (\text{low conc.})} \dots$ $\xrightarrow{Mg, \text{Dry ether}} \dots$ $\xrightarrow{CH_3-CO-CH_3, NH_4Cl} \dots$ $\xrightarrow{H^{+}, \Delta} (X)$. The end product $(X)$ of the above reaction is: