The pH of a solution is 5.9. If the hydrogen ion concentration in decreased hundred times, the solution will be :

Options

A. more acidic
B. neutral
C. less acidic
D. slightly basic

Explanation

To solve the problem, we need to follow these steps:

### Step 1: Calculate the initial hydrogen ion concentration from the given pH.
The formula to calculate the hydrogen ion concentration \([H^+]\) from pH is:
\[ [H^+] = 10^{-\text{pH}} \]
Given that the pH is 5.9:
\[ [H^+] = 10^{-5.9} \approx 1.258 \times 10^{-6} \, \text{mol/L} \]

### Step 2: Decrease the hydrogen ion concentration by 100 times.
To decrease the concentration by 100 times, we divide the initial concentration by 100:
\[ [H^+]_{\text{new}} = \frac{1.258 \times 10^{-6}}{100} = 1.258 \times 10^{-8} \, \text{mol/L} \]

### Step 3: Calculate the new pH from the new hydrogen ion concentration.
Using the pH formula again:
\[ \text{pH}_{\text{new}} = -\log([H^+]_{\text{new}}) \]
Substituting the new concentration:
\[ \text{pH}_{\text{new}} = -\log(1.258 \times 10^{-8}) \approx 7.9 \]

### Step 4: Determine the nature of the solution based on the new pH.
The pH scale ranges from 0 to 14:
- A pH of 7 is neutral.
- A pH less than 7 indicates an acidic solution.
- A pH greater than 7 indicates a basic solution.

Since the new pH is 7.9, which is greater than 7, the solution is slightly basic.

### Final Answer:
The solution will be **slightly basic**.

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