Why are alkanes known as "Paraffins"?

Which of the following is $NOT$ obtained when a mixture of bromomethane and bromoethane is treated with sodium in dry ether?

In Wurtz reaction,alkyl halides react with:

Select the chain propagation steps in the free-radical chlorination of methane.
$(1) \, Cl_2 \to 2Cl^{\bullet}$
$(2) \, Cl^{\bullet} + CH_4 \to CH_3Cl + H^{\bullet}$
$(3) \, Cl^{\bullet} + CH_4 \to CH_3^{\bullet} + HCl$
$(4) \, H^{\bullet} + Cl_2 \to HCl + Cl^{\bullet}$
$(5) \, CH_3^{\bullet} + Cl_2 \to CH_3Cl + Cl^{\bullet}$

Wurtz reaction of bromoethane gives $n$-butane. Sodium salt of $X$ on heating with sodalime also results in $n$-butane. Compound $X$ is

$n$-butane on heating with a catalytic mixture of $AlCl_3$ and $HCl$ gives: