Observe the table below:

Four students observed the colour and odour of acetic acid in its reaction with sodium hydrogen carbonate. They tabulated their observations as above. The correct set of observations is that of the student:

When an acid reacts with a base, salt and water are formed and this reaction is called neutralization reaction.

Now, acetic acid is an acid and sodium bicarbonate is a base.
The reaction is:
${\mathit{CH}}_3\mathit{COOH}+\mathit{NaHC}{O}_3\to {\mathit{CH}}_3\mathit{COONa}+C{O}_2+H_{2}O$

During this reaction, carbon dioxide is formed which is released with a hissing sound which is known as effervescence. Thus, the observations of this reaction are- 
(i) Acetic acid is a colourless liquid.
(ii) It has a smell like vinegar.
(iii) When sodium hydrogen carbonate is added to acetic acid, carbon dioxide is released with effervescence.
Thus, the observations tabulated by Student B are the most accurate.