In organic reactions, sodium in liquid ammonia is used as:

$A$ dibromide $X$ $(C_4H_8Br_2)$ on dehydrohalogenation gave $Y$,which on reduction with $Z$ gave a non-polar isomer of $C_4H_8$. What are $X$ and $Z$ respectively?

Given below are two statements $:$
Statement $I :$ Ozonolysis followed by treatment with $Zn, H_2O$ of $cis-2-butene$ gives ethanal.
Statement $II :$ The product obtained by ozonolysis followed by treatment with $Zn, H_2O$ of $3,6-dimethyloct-4-ene$ has no chiral carbon atom.
In the light of the above statements,choose the correct answer from the options given below.

The product obtained by the reaction of propene with $HBr$ in the presence of peroxide is......

The major product$(s)$ formed in the following reaction sequence is (are):

In the presence of peroxide,hydrogen chloride and hydrogen iodide do not give anti-Markovnikov's addition to alkenes because