Write the structural formula of propanone.

Select the members of a homologous series from the following compounds and arrange them in increasing order of their molecular weights:

${\mathrm{CH}}_3\mathrm{COOH}, {\mathrm{CH}}_3{\mathrm{CH}}_2\mathrm{OH}, {\mathrm{CH}}_3{\mathrm{OCH}}_3, {\mathrm{CH}}_3\mathrm{OH}, {\mathrm{C}}_2{\mathrm{H}}_4, {\mathrm{C}}_2{\mathrm{H}}_6, {\mathrm{CH}}_3{\mathrm{CH}}_2{\mathrm{CH}}_2\mathrm{OH}, {\mathrm{C}}_3{\mathrm{H}}_4$

Write the condition for the reaction of addition of hydrogen to ethylene. Write the balanced chemical equation of the reaction.

Mention one use of CNG.