When $HCl$ is treated with propene in the presence of sodium peroxide,the major product obtained is

$A$ hydrocarbon with molecular formula $C_6H_{10}$ absorbs only one molecule of $H_2$ upon hydrogenation. Ozonolysis of the hydrocarbon yields $OHC-CH_2-CH_2-CH_2-CH_2-CHO$. The hydrocarbon is:

Addition of bromine on propene in the presence of brine yields a mixture of :

Addition of $HCl$ to $3,3$-dimethyl-$1$-butene yields two products,one of which has a rearranged carbon skeleton. Among the following carbocations,select the possible intermediates in that reaction:
$1.$ $(CH_3)_3C-C^+H-CH_3$
$2.$ $(CH_3)_3C-CH_2-C^+H_2$
$3.$ $(CH_3)_2C(Cl)-C^+(CH_3)_2$
$4.$ $(CH_3)_2C^+-CH(CH_3)_2$

Which of the following is the most stable?

Following are the four molecules $P$,$Q$,$R$ and $S$. Which one among the four molecules will react with $HBr_{(aq)}$ at the fastest rate?