Ethylene dibromide ($1$,$2$-dibromoethane) on heating with metallic sodium in ether solution yields:

Identify the reactivity order for halogens towards alkanes.

Choose the chain terminating step.
$(1)$ $H_2 \to H^{\bullet} + H^{\bullet}$
$(2)$ $Br_2 \to Br^{\bullet} + Br^{\bullet}$
$(3)$ $Br^{\bullet} + HBr \to H^{\bullet} + Br_2$
$(4)$ $H^{\bullet} + Br_2 \to HBr + Br^{\bullet}$
$(5)$ $Br^{\bullet} + Br^{\bullet} \to Br_2$

Which of the following alkanes cannot be prepared by the hydrogenation of an olefin?

Kolbe's electrolysis of sodium acetate at the anode gives:

Maximum carbon-carbon bond distance is found in