Ozonolysis of compound $X$ followed by reduction yields two moles of the same aldehyde. What is $X$?

$(R)-3-$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 $Y$?

$But-1-ene \xrightarrow[(ii) NaBH_4]{(i) (CH_3COO)_2Hg/H_2O} ?$
The product in the above reaction is:

Which of the following intermediates is formed to produce the major product in the addition of $HBr$ to propene in the presence of peroxide?

Which hydrogen in compound $(E)$ is easily replaceable during bromination reaction in the presence of light?
$CH_3 - CH_2 - CH = CH_2$
$(E)$

What is the product formed when propene reacts with $N$-bromosuccinimide $(NBS)$ in $CCl_4$?