When glycerol is heated with concentrated sulfuric acid,a substance with a pungent smell is obtained. Which of the following is that compound?

Which of the following is an unsaturated compound?

In hydroboration reaction:
$I$. $Syn$ addition takes place
$II$. Reaction proceeds through formation of a cyclic transition state
$III$. Markovnikov rule is followed in the reaction
$IV$. Anti-addition takes place and anti-Markovnikov rule is followed
Which statement$(s)$ is/are correct?

Which major product is obtained by the addition of $1 \ mol$ of $HCl$ to $1,3$-butadiene at low temperature ($0^{\circ}C$ or below)?

Explain the Anti-Markovnikov rule or peroxide effect (Kharasch effect) or free radical addition reaction with an example.

Aqueous sulphuric acid reacts with $2-$methyl$-1-$butene to give predominantly