Assertion: A solution of sucrose in water is dextrorotatory but on hydrolysis in the presence of little hydrochloric acid, it becomes laevorotatory. 

Reason: Sucrose on hydrolysis gives unequal amounts of glucose and fructose as a result of which change in sign of rotation is observed. 

Assertion is correct but the Reason is incorrect.

Correct reason: Sucrose on hydrolysis gives equal amounts of glucose and fructose. Since fructose is more laevorotatory than glucose is dextrorotatory, therefore, the sign of rotation changes.