Consider the following molecule $(X)$. The reaction of $(X)$ with $HBr$ gives the major product:

$CH_2=CH-CH_2-CH_2-C(OH)(CH_2OH)-CH_2-CH_3$ $\xrightarrow[TsOH]{(CH_3)_2CO}$ $(A)$ $\xrightarrow[{(CH_3)_2S}]{O_3}$ $(B) + HCHO$. Product $(B)$ is

In the reaction of hydrogen bromide with an alkene (in the absence of peroxides),the first step of the reaction is the ................. to the alkene.

How many products will be formed in this reaction?

What is the structure of the $2$-butenyl radical?

In the following reaction,$A$ and $B$ respectively are
$A \xrightarrow{HBr} C_2H_5Br \xrightarrow{B} A$