In which of the following neutralisation reactions, the heat of neutralisation will be highest?
The correct option is A $$HCl$$ and $$NaOH$$
The heat of neutralisation will be highest for the reaction involving strong acid as well as strong base.
Since, $$CH_3COOH$$ is a weak acid and $$NH_4OH$$ is a weak base so the options B,C,D will not have maximum heat of neutralisation, while in option A both $$HCl$$ and $$NaOH$$ are strong so it will have highest heat of neutralisation.
Hence, answer is option A.