Identify the catalyst $$X$$ used in following reaction.

$$\mathrm{CH}_3 \mathrm{CH}_2 \mathrm{Br}+2[\mathrm{H}] \xrightarrow{X} \mathrm{CH}_3-\mathrm{CH}_3+\mathrm{HBr}$$

What type of hybridisation is present in carbocation formed during the alkaline hydrolysis of 1 - bromo-1-phenyl ethane?

The correct order of boiling points of alkyl halides is

$\alpha$-chlorosodium acetate on boiling with aqueous sodium nitrite gives