Alkenes are unsaturated hydrocarbons with the general molecular formula $C_n{H}_{2n}$. Which of the following molecular formulas represents an alkene?

(a) $C_4{H}_{10}$ (b) $C_6{H}_{14}$ (c) $C_8{H}_{16}$ (d) $C_{10}{H}_{22}$

Describe the typical reaction conditions required specifically for the catalytic cracking of long-chain hydrocarbons.

Complete the following equation for the industrial cracking of octadecane ($C_{18}{H}_{38}$):

$C_{18}{H}_{38}\to C_{12}{H}_{26}+2\_\_\_\_$

Explain, in terms of intermolecular forces, why the reactant $C_{18}{H}_{38}$ has a significantly higher boiling point than the product $C_{12}{H}_{26}$.