The halogen which is most reactive in the free radical halogenation of alkanes under sunlight is

What is $Z$ in the following reaction?
$CH_3-CH_2-CO_2^{\ominus} Na^{\oplus} \stackrel{NaOH / CaO}{\longrightarrow} Z$

Consider the given sequence of reactions.
$C_2H_6 + \frac{3}{2}O_2$ $\xrightarrow[\Delta]{(CH_3COO)_2Mn} X$ $\xrightarrow{NaOH} Y$
Electrolysis of aqueous solution of $Y$ gives gases $P$ and $Q$ at anode. $P$ and $Q$ are respectively.

What are $X$ and $Y$ in the following reaction sequence?
Iso-pentane $\xrightarrow{KMnO_4} X$ $\xrightarrow[358 \ K]{20 \% H_3PO_4} Y$

Of the $5$ isomeric hexanes,the isomer which can give $2$ monochlorinated compounds is

What is the number of moles of secondary carbon atoms in $n \ mol$ of isopentane?