To prepare `100 g` of a 92% by weight solution of `NaOH` how many `g` of `H_(2) O`is needed?

Options

A. 9 g
B. 8g
C. 10 g
D. 11g

Explanation

To prepare 100 g of a 92% by weight solution of NaOH, we need to determine how much water (H₂O) is required. Here’s the step-by-step solution:

### Step 1: Understand the percentage concentration
A 92% by weight solution means that in every 100 g of the solution, 92 g is the solute (NaOH) and the rest is the solvent (water).

### Step 2: Calculate the mass of NaOH
From the problem, we know:
- Total mass of the solution = 100 g
- Mass of NaOH = 92 g

### Step 3: Calculate the mass of water
To find the mass of water, we subtract the mass of NaOH from the total mass of the solution:
\[ \text{Mass of H₂O} = \text{Total mass of solution} - \text{Mass of NaOH} \]
\[ \text{Mass of H₂O} = 100 \, \text{g} - 92 \, \text{g} = 8 \, \text{g} \]

### Conclusion
Thus, to prepare 100 g of a 92% by weight solution of NaOH, you need **8 g of H₂O**.

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