Which of the following is most reactive towards $EAR$ (Electrophilic Addition Reaction)?

The number of alkene$(s)$ which can produce $2-butanol$ by the successive treatment of $(i)$ $B_{2}H_{6}$ in tetrahydrofuran solvent and $(ii)$ alkaline $H_{2}O_{2}$ solution is:

What is the product formed when $CH_2 = CH(CH_2)_2COOH$ reacts with $HBr$?

Consider the following reactions:
$Ph-CH_2-CH=CH_2 \xrightarrow{H^+/H_2O} P$
$Ph-CH_2-CH=CH_2 \xrightarrow[(ii) NaBD_4]{(i) Hg(OAc)_2, H_2O} Q$
$Ph-CH_2-CH=CH_2 \xrightarrow[(ii) H_2O_2/OH^-]{(i) BD_3, THF} R$
Identify the products $P, Q$ and $R$.

Alkene can be prepared from alkyl halide by the following reagent: $R-CH_2-CH_2-X + \text{Base} \to \text{Alkene} + \text{Base-H} + X^-$

The reaction of $4$-methyloct$-1-$ene $(P, 2.52 \ g)$ with $HBr$ in the presence of $(C_6H_5CO_2)_2O_2$ gives two isomeric bromides in a $9:1$ ratio,with a combined yield of $50 \%$. Of these,the entire amount of the primary alkyl bromide was reacted with an appropriate amount of diethylamine followed by treatment with aqueous $K_2CO_3$ to give a non-ionic product $S$ in $100 \% $ yield. The mass (in $mg$) of $S$ obtained is. . . . . . . [Use molar mass (in $g \ mol^{-1}$) : $H=1, C=12, N=14, Br=80$]