Draw the electron dot structure of ethyne and also draw its structural formula.

Give names of the following:
$(a)$ An alcohol containing $4$ carbon atoms.
$(b)$ An acid with $5$ carbon atoms.
$(c)$ Simplest ketone. Define functional group in a carbon compound. Mention names of any three functional groups with their formulae and example.

$(a)$ Complete the following equations:
$(i)$ $CH_4 + 2O_2 \longrightarrow CO_2 + 2H_2O + \text{Heat} + \text{Light}$
$(ii)$ $CH_3COOH + C_2H_5OH \xrightarrow{\text{Acid}} CH_3COOC_2H_5 + H_2O$
$(iii)$ $CH_3CH_2OH \xrightarrow[\text{443 K}]{\text{Conc. } H_2SO_4} CH_2=CH_2 + H_2O$

$(a)$ Soaps cannot be used with hard water. Why?
$(b)$ Give the chemical composition of detergents.
$(c)$ Give one advantage of detergents over soaps.

What is the molecular formula of vinegar used as a preservative?

Which substance is produced by the oxidation of methanal in the presence of an oxidising agent?