`4.0` g of NaOH and `4.9` g of `H_(2)SO_(4)` are dissolved in water and volume is made upto 250 mL.
The pH of this solution is:

Options

A. `7.0`
B. `1.0`
C. `2.0`
D. `12.0`

Answer

To find the pH of the solution formed by dissolving 4.0 g of NaOH and 4.9 g of H₂SO₄ in water, we can follow these steps:

### Step 1: Calculate the number of moles of NaOH
- Given weight of NaOH = 4.0 g
- Molecular weight of NaOH = 40 g/mol

\[ \text{Number of moles of NaOH} = \frac{\text{Weight}}{\text{Molecular Weight}} = \frac{4.0 \, \text{g}}{40 \, \text{g/mol}} = 0.1 \, \text{mol} \]

### Step 2: Calculate the number of moles of H₂SO₄
- Given weight of H₂SO₄ = 4.9 g
- Molecular weight of H₂SO₄ = 98 g/mol

\[ \text{Number of moles of H₂SO₄} = \frac{4.9 \, \text{g}}{98 \, \text{g/mol}} = 0.05 \, \text{mol} \]

### Step 3: Determine the number of H⁺ ions produced by H₂SO₄
- Each mole of H₂SO₄ produces 2 moles of H⁺ ions.

\[ \text{Number of H⁺ ions} = 2 \times \text{Number of moles of H₂SO₄} = 2 \times 0.05 \, \text{mol} = 0.1 \, \text{mol} \]

### Step 4: Compare the moles of H⁺ and OH⁻ ions
- From Step 1, we have 0.1 mol of OH⁻ from NaOH.
- From Step 3, we have 0.1 mol of H⁺ from H₂SO₄.

Since the number of moles of H⁺ ions (0.1 mol) is equal to the number of moles of OH⁻ ions (0.1 mol), they will completely neutralize each other.

### Step 5: Determine the pH of the solution
- When H⁺ and OH⁻ ions neutralize each other, they form water, which has a neutral pH of 7.

Thus, the pH of the solution is:

\[ \text{pH} = 7 \]

### Final Answer
The pH of the solution is **7**.

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