Which of the following pairs can be distinguished by Fehling’s solution ?

Glucose is a hemiacetal, so in presence of a base (alkaline medium is provided by Fehling’s solution) it can develop −CHO group in the form of open chain structure which responds Fehling’s solution. Sucrose is a glycoside (acetal) i.e. its hemiacetal OH groups (one due to glucose and another due to fructose) are not free, so it can’t attain −CHO group. Hence it will not respond Fehling’s solution.