The pKw of water at `50^@C` is 13.40. An aqueous solution at `50^@C` has pH= 7. This solution is–

Options

A. Acidic
B. alkaline
C. Neutral
D. Amphoteric

Answer

To determine the nature of the aqueous solution at 50°C with a pH of 7, we can follow these steps:

### Step 1: Understand the relationship between pKw and pH
The pKw of water at 50°C is given as 13.40. The relationship between pKw and pH is given by the formula:
\[ \text{pH} + \text{pOH} = \text{pKw} \]

### Step 2: Calculate the pOH
Using the pKw value, we can calculate the pOH:
\[ \text{pOH} = \text{pKw} - \text{pH} \]
Substituting the values:
\[ \text{pOH} = 13.40 - 7 = 6.40 \]

### Step 3: Determine the nature of the solution
In pure water at 50°C, the pH is considered neutral at 6.7 (which is half of the pKw). Since the pH of our solution is 7, we can compare it to the neutral pH:
- If pH < 6.7, the solution is acidic.
- If pH = 6.7, the solution is neutral.
- If pH > 6.7, the solution is basic (alkaline).

Since 7 > 6.7, the solution is basic.

### Conclusion
The aqueous solution at 50°C with a pH of 7 is alkaline.