Assertion (A): `E_(Ag^(+)//Ag)` increases with increase in concentration of `Ag^(+)` ions.
Reason (R): `E_(Ag^(+)//Ag)` has a positive value.

Options

A. Both A and R are true but R is NOT the correct explanation of A
B. Both A and R are true but R is NOT the correct explanation of A
C. A is true but R is false
D. A is false and R is True

Explanation

To solve the question regarding the assertion and reason about the electrochemical cell involving silver ions, we will break down the concepts step by step.

### Step 1: Understand the Assertion
The assertion states that the standard electrode potential \( E_{Ag^+//Ag} \) increases with an increase in the concentration of \( Ag^+ \) ions.

### Step 2: Write the Half-Cell Reaction
The half-cell reaction for silver ions can be written as:
\[ Ag^+ + e^- \rightarrow Ag \]

### Step 3: Use the Nernst Equation
The Nernst equation relates the standard electrode potential to the concentration of the ions involved in the reaction:
\[ E_{cell} = E^0_{cell} - \frac{0.059}{n} \log \left( \frac{[Ag]}{[Ag^+]} \right) \]
Here, \( n = 1 \) for the reaction involving one electron.

### Step 4: Substitute Values
Assuming the concentration of solid silver \( [Ag] \) is constant (as it is a pure solid), we can simplify the equation:
\[ E_{cell} = E^0_{cell} - 0.059 \log \left( \frac{1}{[Ag^+]} \right) \]
This can be rewritten as:
\[ E_{cell} = E^0_{cell} + 0.059 \log [Ag^+] \]

### Step 5: Analyze the Effect of Increasing \( [Ag^+] \)
From the equation \( E_{cell} = E^0_{cell} + 0.059 \log [Ag^+] \):
- As the concentration of \( Ag^+ \) increases, \( \log [Ag^+] \) increases.
- Therefore, \( E_{cell} \) increases with an increase in \( [Ag^+] \).

### Step 6: Understand the Reason
The reason states that \( E_{Ag^+//Ag} \) has a positive value. This is true because the standard electrode potential for the reduction of silver ions is positive, indicating that the reaction is favorable under standard conditions.

### Conclusion
Both the assertion and reason are true:
- Assertion (A) is true: \( E_{Ag^+//Ag} \) increases with an increase in concentration of \( Ag^+ \) ions.
- Reason (R) is true: \( E_{Ag^+//Ag} \) has a positive value.
However, the reason does not explain why the assertion is true. Therefore, the correct answer is that both statements are true, but R is not the correct explanation of A.

### Final Answer
The answer is option 2: Both A and R are true, but R is not the correct explanation of A.