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

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:

The metal used for the de-bromination reaction of $1, 2$-dibromoethane is:

Oils are converted into fats by

The reaction is given as:
$(CH_3)_2C=C(CH_3)_2 + (CH_3)_3N^{+}-O^{-} + H_2O \xrightarrow{OsO_4 (10^{-4} \text{ mole})} A + (CH_3)_3N$
Product $(A)$ is:

$HCl$ does not show the peroxide effect because the reaction mechanism involves the following steps:
$CH_3-CH=CH_2 + \dot{X} \to CH_3-\dot{C}H-CH_2X$ $(I)$
$CH_3-\dot{C}H-CH_2X + HX \to CH_3-CH_2-CH_2X + \dot{X}$ $(II)$
Why does $HCl$ fail to undergo this reaction?