Consider the following reaction sequence

$ \text { 2-methylpropane } \xrightarrow{\mathrm{KMnO}_{4}} X \xrightarrow[358 \mathrm{~K}]{20 \% \mathrm{H}_3 \mathrm{PO}_4} Y \xrightarrow[\text { (ii) } \mathrm{Zn} / \mathrm{H}_{2} \mathrm{O}]{\text { (i) } \mathrm{O}_{3}} A+B \text {. } $

What are $A$ and $B$ ?

What are $Y$ and $Z$ respectively in the given reaction sequence?

The alkane which is next to methane in homologous series can be prepared from which of the following reactions?

$ \text { I. } 2 \mathrm{CH}_{3} \mathrm{Br} \xrightarrow[\text { Dry ether }]{\mathrm{Na}} $

II. $\mathrm{CH}_{3} \mathrm{COOH} \xrightarrow[\mathrm{CaO}, \Delta]{\mathrm{NaOH}}$

III. $\mathrm{CH}_{3} \mathrm{CH}=\mathrm{CH}_{2} \xrightarrow{\mathrm{H}_{2} / \mathrm{Pt}}$ IV. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{Br} \xrightarrow[\mathrm{H}^{+}]{\mathrm{Zn}}$