When fructose treated with Tollen's reagent, silver mirror is formed due to reduction of `Ag^(o+)` by:

Options

A. fructose itself
B. glucose formed by isomerisation
C. mannose formed by isomerisation
D. galactose formed by isomerisation

Explanation

To solve the question regarding the formation of a silver mirror when fructose is treated with Tollen's reagent, we will follow these steps:

### Step 1: Understanding Fructose Structure
Fructose is a ketose sugar, which means it contains a ketone group rather than an aldehyde group. Its structure can be represented as:
- CH₂OH
- C=O (ketone)
- Several hydroxyl (OH) groups

### Step 2: Tollen's Reagent Mechanism
Tollen's reagent (Ag(NH₃)₂⁺) is used to test for aldehydes. Aldehydes can reduce Tollen's reagent, leading to the formation of a silver mirror. Since fructose does not have an aldehyde group, it would not react directly with Tollen's reagent.

### Step 3: Isomerization of Fructose
However, fructose can undergo isomerization to form glucose or mannose, both of which contain aldehyde groups. This isomerization occurs in the presence of a base, where fructose can rearrange to form these aldoses.

### Step 4: Reaction with Tollen's Reagent
When fructose is isomerized to glucose or mannose, these resulting sugars can then react with Tollen's reagent. The aldehyde group in glucose or mannose will reduce the Tollen's reagent, resulting in the formation of a silver mirror.

### Step 5: Conclusion
Thus, the silver mirror is formed due to the reduction of Ag⁺ by the aldehyde groups present in the isomerized forms of fructose, specifically glucose and mannose.

### Final Answer
The correct answer is that the silver mirror is formed due to the reduction of Ag⁺ by glucose and mannose, which are formed by isomerization of fructose.

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