Which of the following gives a ketone on oxidation?

An alcohol $X$ $(C_5H_{12}O)$ on dehydration gives $Y$ (major product). Reaction of $Y$ with $HBr$ gave $Z$ ($C_5H_{11}Br$,major product). $Z$ undergoes nucleophilic substitution in two steps. What are $X$ and $Y$?

Which compound has the highest boiling point?

Dehydrogenation of $CH_3-CH(OH)-CH_3$ gives

What is obtained by the oxidation of isopropyl alcohol?

$CHO-CH(OH)-CH_2OH \xrightarrow{2HIO_4}$ Products obtained in the above reaction are