Ammonia is always added in this reaction. Which of the following must be incorrect

Options

A. `NH_(3)` combines with `Ag^(+)` to form a complex
B. `Ag(NH_(3))_(2)^(+)` is a stronger oxidising reagent than `Ag^(+)`
C. In absence of `NH_(3)` silver salt of gluconic acid is formed
D. `NH_(3)` has affected the standard reduction potential of glucose/gluconic acid electrode

Explanation

To solve the question regarding the addition of ammonia in a reaction and determine which statement must be incorrect, we will analyze each option step by step.

### Step 1: Understand the Reaction
The reaction involves the reduction of silver ions (Ag⁺) to silver (Ag) with the involvement of ammonia (NH₃). The standard reduction potential for the reaction Ag⁺ + e⁻ → Ag is given as 0.8 volts.

### Step 2: Analyze Each Option
1. **Option 1:** NH₃ combines with Ag⁺ to form a complex.
- When NH₃ combines with Ag⁺, it forms the complex [Ag(NH₃)₂]⁺. This is a well-known reaction and is correct.
- The reduction potential for this complex is 0.33 volts, which is lower than that of Ag⁺, indicating that this statement is correct.

2. **Option 2:** The complex [Ag(NH₃)₂]⁺ is a stronger oxidizing agent than Ag⁺.
- Since the reduction potential of [Ag(NH₃)₂]⁺ (0.33 volts) is lower than that of Ag⁺ (0.8 volts), it means that [Ag(NH₃)₂]⁺ is a weaker oxidizing agent than Ag⁺. Therefore, this statement is incorrect.

3. **Option 3:** In the absence of NH₃, silver salt of glycanic acid is formed.
- This statement suggests that without NH₃, a reaction occurs that produces a silver salt of glycanic acid. This is a plausible reaction, and thus this statement is correct.

4. **Option 4:** NH₃ has affected the standard reduction potential of glucose and glycanic acid electrode.
- The statement claims that NH₃ affects the standard reduction potential. However, NH₃ does not influence the standard reduction potential of glucose and glycanic acid electrodes significantly. Therefore, this statement is also incorrect.

### Conclusion
From the analysis, the incorrect statements are:
- **Option 2:** The complex [Ag(NH₃)₂]⁺ is a stronger oxidizing agent than Ag⁺.
- **Option 4:** NH₃ has affected the standard reduction potential of glucose and glycanic acid electrode.

However, since the question asks for which must be incorrect, the primary incorrect statement is **Option 2**.

### Final Answer
The incorrect statement is: **The complex [Ag(NH₃)₂]⁺ is a stronger oxidizing agent than Ag⁺.**