Give balanced equations for the laboratory preparations of:

(i) A saturated hydrocarbon from iodomethane.

(ii) An unsaturated hydrocarbon from an alcohol.

(iii) An unsaturated hydrocarbon from calcium carbide.

(iv) An alcohol from ethyl bromide.

(i) Methane is produced

$\underset{\text{ methyl iodide}}{\text{CH}$3\text{I}} + \underset{ \text{ nascent hydrogen}}{2\text{[H]}} \underset{\text{alcohol}}{\xrightarrow{\text{Zn/Cu couple}}} \underset{ \text{ methane}}{\text{CH}4} + \text{HI}

(ii) Ethene is formed

$\underset{\text{ ethyl alcohol}}{\text{C}$2\text{H}5\text{OH}} \xrightarrow[170\degree\text{C}]{\text{Conc. H}2\text{SO}4\text{[excess]}} \underset{ \text{ethene}}{\text{C}2\text{H}4} + \text{H}_2\text{O}\

(iii) Ethyne is formed

$\underset{\text{calcium carbide}}{\text{CaC}$2} + \underset{\text{water}}{2\text{H}2\text{O}} \longrightarrow \underset{\text{ethyne [acetylene]}}{\text{C}2\text{H}2} + \text{Ca(OH)}_2

(iv) ethyl alcohol is formed.

$\underset{\text{ Bromoethane [ethyl bromide]}}{\text{C}$2\text{H}5\text{-Br}} + \underset{\text{ alcoholic KOH}}{\text{KOH [aq.]}} \xrightarrow{\text{boil}} \underset{ \text{ ethyl alcohol}} {\text{C}2\text{H}5\text{OH}} + \text{KBr}