Step 1: Write the structure of 1-chlorobutane.
1-chlorobutane is
\[
\mathrm{CH_3CH_2CH_2CH_2Cl}
\]
Step 2: Reaction with aqueous KOH.
Aqueous KOH provides \(\mathrm{OH^-}\) ions and favours nucleophilic substitution.
So, chlorine is replaced by \(\mathrm{OH}\).
\[
\mathrm{CH_3CH_2CH_2CH_2Cl+KOH(aq)\rightarrow CH_3CH_2CH_2CH_2OH+KCl}
\]
Hence,
\[
P=\text{Butan-1-ol}
\]
Step 3: Reaction with alcoholic KOH.
Alcoholic KOH favours elimination reaction.
So, HCl is removed from 1-chlorobutane to form an alkene.
\[
\mathrm{CH_3CH_2CH_2CH_2Cl+KOH(alc)\rightarrow CH_3CH_2CH=CH_2+KCl+H_2O}
\]
Hence,
\[
Q=\text{But-1-ene}
\]
Step 4: Final conclusion.
Therefore,
\[
\boxed{P=\text{Butan-1-ol},\quad Q=\text{But-1-ene}}
\]