The addition of $HBr$ is easiest with

Identify the correct statements with respect to $cis/trans$-but$-2$-ene from the following:
$I$. $cis$-but$-2$-ene is more polar than $trans$-but$-2$-ene
$II$. Melting point of $cis$-but$-2$-ene is greater than that of $trans$-but$-2$-ene
$III$. Boiling point of $cis$-but$-2$-ene is greater than that of $trans$-but$-2$-ene
Correct answer is

Give the order of stability for different alkenes.

Identify the relationship between $A$ and $B$ in the following reactions:
$CH_3-CH=CH_2 \xrightarrow[(2)H_2O_2, OH^-]{(1)BH_3-THF} A$
$CH_3-CH=CH_2 \xrightarrow[(2)NaBH_4]{(1)(AcO)_2Hg, H_2O} B$

An organic compound $(A)$ on ozonolysis followed by treatment with zinc dust and water gives product $(P)$,which can be used to preserve biological specimens. Identify $(A)$.

The addition reaction of $1,3$-butadiene with bromine yields ........