$CH_3-CH_2-CH=CH_2 \xrightarrow[CCl_4]{Br_2} \text{Product}$

One mole of each of the following alkenes is catalytically hydrogenated. The quantity of heat evolved will be the lowest in the case of

Major product '$P$' formed in the following reaction is:-

Identify $X, Y$ and $Z$ in the following reactions:

Given below are two statements: one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R)$.
Assertion $(A)$: Cis form of alkene is found to be more polar than the trans form.
Reason $(R)$: Dipole moment of trans isomer of $2$-butene is zero.
In the light of the above statements,choose the correct answer from the options given below:

Addition of bromine to $1,3-$butadiene gives