$A$ compound '$X$' on ozonolysis forms two molecules of $HCHO$. Compound '$X$' is

$(R)-3-$bromocyclopentene (shown below) reacts with $Br_2/CCl_4$ to form two products,$Y$ and $Z$. $Y$ is not optically active (does not rotate plane-polarized light). What is the structure of $Y$?

The product of the following reaction is:
$CH_3CH_2CH_2CH=CH_2 \xrightarrow[(ii) H_2O_2, OH^-]{(i) BH_3/THF} \text{Product}$

The major product of this reaction is:

The major product $[B]$ in the following sequence of reactions is
$CH_3-C(CH(CH_3)_2)=CH-CH_2CH_3$ $\xrightarrow[(i) B_2H_6]{(ii) H_2O_2, OH^{-}} [A]$ $\xrightarrow[\Delta]{dil. H_2SO_4} [B]$

The major products $P$ and $Q$ from the below reactions are :
$CH_3CH=CH_2 \xrightarrow{HBr} P$
$CH_3CH=CH_2 \xrightarrow[(BH_3)_2]{H_2O, H_2O_2 / OH^-} Q$