46 g of sodium chloride is dissolved in 100 g of water at 293 K. Find its concentration at this temperature.

Options

A. 21%
B. 23%
C. 31.5%
D. 40%

Explanation

To find the concentration of sodium chloride (NaCl) in the solution, we will follow these steps:

### Step 1: Identify the mass of solute and solvent
- Mass of sodium chloride (NaCl) = 46 g
- Mass of water (solvent) = 100 g

### Step 2: Calculate the mass of the solution
The mass of the solution is the sum of the mass of the solute and the mass of the solvent.
\[ \text{Mass of solution} = \text{Mass of solute} + \text{Mass of solvent} = 46 \, \text{g} + 100 \, \text{g} = 146 \, \text{g} \]

### Step 3: Calculate the concentration
Concentration (in percentage) is calculated using the formula:
\[ \text{Concentration} = \left( \frac{\text{Mass of solute}}{\text{Mass of solution}} \right) \times 100 \]
Substituting the values we have:
\[ \text{Concentration} = \left( \frac{46 \, \text{g}}{146 \, \text{g}} \right) \times 100 \]

### Step 4: Perform the calculation
Calculating the fraction:
\[ \frac{46}{146} \approx 0.3151 \]
Now, multiplying by 100 to get the percentage:
\[ \text{Concentration} \approx 0.3151 \times 100 \approx 31.51\% \]

### Final Answer
The concentration of sodium chloride in the solution is approximately **31.5%**.

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