Vinay was trying to create sodium acetate, he added ethanoic acid and ‘A’ in an open vessel. He also added few drops of concentrated $H_{2}S{O}_4$ to this and was surprised when the solution gave a sweet effervescence. So he repeated this experiment in a closed vessel and obtained ethyl acetate. Then he added ‘B’ and created sodium acetate. Find A and B.

The correct option is C A - Ethanol; B - Sodium hydroxide
Esters are formed by the reaction of an acid and an alcohol. Ethanoic acid reacts with absolute ethanol in the presence of an acid catalyst to give an ester.
$C{H}_{3}COOH+C{H}_{3}C{H}_{2}OH+Acidcatalyst\to C{H}_{3}COO{C}_2{H}_5\left(Ester\right)$
Esters are sweet smelling substances and are highly volatile. Hence when conducted in an open vessel, it evaporated. On treating with sodium hydroxide, which is an alkali, the ester is converted back to alcohol and sodium salt of carboxylic acid. This reaction is known as saponification because it is used in the preparation of soap.
$C{H}_{3}COO{C}_2{H}_5+NaOH\to C_2{H}_{5}OH+C{H}_{3}COONa$