The pH of a sample of pure water is 7 at room temperature. What will be its pH when a pinch of solid baking soda is dissolved in it?
Very near to 7
Less than 7
More than 7
Exactly 7

Options

A. Very near to 7
B. Less than 7
C. More than 7
D. Exactly 7

Answer

To determine the pH of pure water after dissolving a pinch of solid baking soda (sodium bicarbonate, NaHCO3), we can follow these steps:

### Step 1: Understand the pH of Pure Water
- The pH of pure water at room temperature is 7, which is considered neutral.

### Step 2: Identify the Nature of Baking Soda
- Baking soda (sodium bicarbonate, NaHCO3) is a basic compound. When it dissolves in water, it dissociates into sodium ions (Na⁺) and bicarbonate ions (HCO₃⁻).

### Step 3: Effect of Baking Soda on pH
- Since baking soda is a base, adding it to water will increase the concentration of hydroxide ions (OH⁻) in the solution. This will shift the pH above 7, making the solution basic.

### Step 4: Analyze the Options
- The options provided are:
- Very near to 7
- Less than 7
- More than 7
- Exactly 7

### Step 5: Eliminate Incorrect Options
- **Less than 7**: This cannot be true since we are adding a base.
- **Exactly 7**: This cannot be true either, as the addition of a base will change the pH.
- **Very near to 7**: While it may not be drastically high, it will still be above 7 due to the basic nature of baking soda.

### Step 6: Conclusion
- The only viable option left is **More than 7**. The pH will increase due to the basic nature of baking soda.

### Final Answer
- The pH of the solution after adding a pinch of baking soda will be **More than 7**.

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