1 kg of water contains 4g of NaOH. The concentration of the solution is:

Options

A. decinormal
B. about 0.1 mole
C. 0.1 molal
D. 0.1 molar

Explanation

To find the concentration of the NaOH solution, we can follow these steps:

### Step 1: Identify the given values
- Mass of NaOH = 4 g
- Mass of water (solvent) = 1 kg = 1000 g

### Step 2: Calculate the molar mass of NaOH
The molar mass of NaOH can be calculated as follows:
- Sodium (Na) = 23 g/mol
- Oxygen (O) = 16 g/mol
- Hydrogen (H) = 1 g/mol

So, the molar mass of NaOH = 23 + 16 + 1 = 40 g/mol.

### Step 3: Calculate the number of moles of NaOH
To find the number of moles of NaOH, we use the formula:
\[ \text{Number of moles} = \frac{\text{mass of solute}}{\text{molar mass of solute}} \]
Substituting the values:
\[ \text{Number of moles of NaOH} = \frac{4 \text{ g}}{40 \text{ g/mol}} = 0.1 \text{ mol} \]

### Step 4: Calculate the concentration of the solution
Concentration (C) is defined as the number of moles of solute per liter of solution. Since we have 1 kg of water, we can assume the volume of the solution is approximately 1 L (since the density of water is about 1 g/mL).

Thus, the concentration of the solution is:
\[ C = \frac{\text{Number of moles of NaOH}}{\text{Volume of solution in liters}} = \frac{0.1 \text{ mol}}{1 \text{ L}} = 0.1 \text{ mol/L} \]

### Final Answer
The concentration of the NaOH solution is **0.1 mol/L**.

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