Which compound gives lactic acid on hydrolysis after reacting with $HCN$?

$CH_3-CH=CH-CH(OH)-CH_3 \xrightarrow{\text{Jones reagent}} X$,
Product $X$ is

Which of the following is a hemiacetal?

Which of the following reactions will not result in the formation of carbon-carbon bonds?

The dipole moment is the highest for

An alkene $A$ $(C_4H_8)$ exhibits cis/trans isomerism. $A$ on ozonolysis gives $B$,which when reacted with $NaOH$ followed by hydroxylamine gives $C$. What are $B$ and $C$?