Sucrose dosent give positive test with Tollens reagent. Why ?

Sugars are of two types, reducing sugar and non reducing sugar. Those sugar molecules which have a free aldehydic and ketonic group and can reduce Tollen's and Fehling reagents are called reducing sugars. For example, glucose.

Sucrose is a non reducing sugar as the OH groups at the both the anomeric carbon atoms are involved in a bond.

Hence sucrose will not give Benedict's test, Fehling's test and tollen's test, which is given readily by most of the aldehydes