Tollens Test

The Tollens test is a chemical test used to detect the presence of aldehydes. This test is based on the reaction between an aldehyde and Tollens' reagent, which consists of silver nitrate (AgNO3) dissolved in aqueous ammonia (NH3). When an aldehyde is present, it reduces the silver ions in Tollens' reagent to metallic silver, forming a silver mirror on the inner surface of the reaction vessel.

Compounds in the Tollens Test

The Tollens test can be used to distinguish between aldehydes and ketones. Ketones do not react with Tollens' reagent and therefore do not produce a silver mirror. However, aldehydes readily react with Tollens' reagent and produce a positive test result.

Compounds in the Given List

Let's analyze each compound in the given list to determine whether it will give a negative or positive Tollens test result.

1. Sucrose: Sucrose is a disaccharide composed of glucose and fructose units linked together. It does not contain an aldehyde functional group and therefore will not react with Tollens' reagent. Sucrose will give a negative Tollens test.

2. Lactose: Lactose is also a disaccharide composed of glucose and galactose units linked together. Similar to sucrose, lactose does not contain an aldehyde functional group and will not react with Tollens' reagent. Lactose will give a negative Tollens test.

3. Maltose: Maltose is a disaccharide composed of two glucose units linked together. Like sucrose and lactose, it does not contain an aldehyde functional group and will not react with Tollens' reagent. Maltose will give a negative Tollens test.

4. Glucose: Glucose is a monosaccharide and an aldehyde. It contains an aldehyde functional group (CHO) and will readily react with Tollens' reagent. Glucose will give a positive Tollens test.

5. Mannose: Mannose is also a monosaccharide and an aldehyde. It contains an aldehyde functional group (CHO) and will react with Tollens' reagent. Mannose will give a positive Tollens test.

Conclusion

Out of the given compounds, only glucose will give a negative Tollens test. This is because glucose is the only compound that contains an aldehyde functional group necessary for the reaction with Tollens' reagent. The other compounds (sucrose, lactose, maltose, and mannose) do not contain an aldehyde functional group and will not react with Tollens' reagent, resulting in a negative test result.