Which of the following reagents cannot be used for the experimental reduction of a functional group?

What is $A$ in the following reaction?
$C_6H_5-CH_2-CH=CH_2 + HCl \rightarrow A$

Identify the correct stability order of the following alkenes:
$I) (CH_3)_2C=C(CH_3)_2$
$II) (CH_3)_2C=CH_2$
$III) (CH_3)_2C=CHCH_3$

$CH_3-CH(CH_3)-CH=CH_2 + HBr \to X$ (major product). $X$ is:

Which of the following alkenes does not exhibit regioselectivity according to $M.K.$ (Markownikoff's) rule?

Compound $X$ on heating with $Zn$ dust gives compound $Y$,which on treatment with $O_3$ followed by reaction with $Zn$ dust and $H_2O$ gives propionaldehyde. The structure of $X$ is: