A carbonyl compound reacts with hydrogen cyanide to form cyanohydrin which on hydrolysis forms a racemic mixture of a α-hydroxy acid. The carbonyl compound is

The carbonyl compound will be acetaldehyde, so when the acetaldehyde reacts with hydrogen cyanide, then there is formation of cyanohydrin, (퐶퐻3퐶퐻(푂퐻)(퐶푁)) and when it is hydrolyzed the cyanide group will convert into carboxylic group 퐶퐻3퐶퐻(푂퐻)(퐶푂푂퐻). So, in this product the carbon atom is joined to all different compounds, hence it will give racemic mixture of alpha-hydroxy acid.