(a) Write the equation for the preparation of carbon tetrachloride from methane.

(b) Draw the structural formula of ethyne.

(c) How is the structure of alkynes different from that of alkenes?

(a) Carbon tetrachloride from methane

$\underset{\text{ methane} }{\text{CH}$4} + \text{Cl}2 \xrightarrow[\text{or 600K}]{\text{diffused sunlight}} \text{CH}_3\text{Cl} + \text{HCl}

$\underset{\text{ chloromethane} }{\text{CH}$3\text{Cl}} + \text{Cl}2 \longrightarrow \underset{\text{dichloromethane}}{\text{CH}2\text{Cl}2}+ \text{HCl}

$\underset{\text{dichloromethane}}{\text{CH}$2\text{Cl}2} + \text{Cl}2 \longrightarrow \underset{\text{trichloromethane}}{\text{CH}\text{Cl}3}+ \text{HCl}

$\underset{\text{trichloromethane}}{\text{CHCl}$3} + \text{Cl}2 \longrightarrow \underset{\text{tetrachloromethane}}{\text{CCl}_4}+ \text{HCl}

(b) Structural formula of ethyne is shown below:

(c) Alkynes contain triple bonds while alkenes contain double bonds.