In the reaction of $1$-bromo-$3$-chlorocyclobutane with two equivalents of sodium in ether,the major product is

An alkyl bromide $(X)$ reacts with $Na$ in the presence of dry ether to form $4, 5-$diethyloctane. Compound $(X)$ is

Electrolysis of an aqueous solution containing sodium acetate and sodium propionate yields ..........

The compound having only primary hydrogen atoms is

The correct order of reactivity of $(I)$,$(II)$,and $(III)$ towards addition reactions is:
$(I)$ Cyclopropane
$(II)$ Cyclobutane
$(III)$ Cyclopentane

$(CH_3)_2CHBr$ $\xrightarrow[(2) CuI]{(1) Li} (A)$ $\xrightarrow{(CH_3)_2CHCH_2Br} B$.
$'B'$ is