Acetaldehyde reacts with hydrogen cyanide via. nucleophilic addition to give acetaldehyde cyanohydrin which then reacts with two moles of water and one mole of hydrochloric acid and than heated. What will be the final product of the reaction?   

Lactic acid 

The correct answer is option 2. Lactic acid.

When acetaldehyde (\( \text{CH}_3\text{CHO} \)) reacts with hydrogen cyanide (HCN) via nucleophilic addition, it forms acetaldehyde cyanohydrin (\( \text{CH}_3\text{CH(OH)CN} \)). Acetaldehyde cyanohydrin (\( \text{CH}_3\text{CH(OH)CN} \)) reacts with two moles of water (\( \text{H}_2\text{O} \)) and one mole of hydrochloric acid (\( \text{HCl} \)) under acidic conditions. This process is known as acid hydrolysis. Acid hydrolysis of acetaldehyde cyanohydrin (\( \text{CH}_3\text{CH(OH)CN} \)) typically results in the formation of lactic acid (\( \text{CH}_3\text{CH(OH)COOH} \)).

The final product of the reaction, after acid hydrolysis and heating, is **lactic acid** (\( \text{CH}_3\text{CH(OH)COOH} \)).