4 g of NaOH dissolved in 100 ml solution. Molarity of the solution is

Options

A. 1 M
B. 10 M
C. 0.1 M
D. 4 M

Answer

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

### Step 1: Calculate the number of moles of NaOH
To calculate the number of moles, we use the formula:

\[ \text{Number of moles} = \frac{\text{mass (g)}}{\text{molar mass (g/mol)}} \]

Given:
- Mass of NaOH = 4 g
- Molar mass of NaOH = 40 g/mol

Substituting the values:

\[ \text{Number of moles} = \frac{4 \, \text{g}}{40 \, \text{g/mol}} = 0.1 \, \text{mol} \]

### Step 2: Convert the volume of the solution from mL to L
Since molarity is expressed in moles per liter, we need to convert the volume from milliliters to liters.

Given:
- Volume of solution = 100 mL

To convert mL to L, we use the conversion factor:

\[ 1 \, \text{L} = 1000 \, \text{mL} \]

So,

\[ \text{Volume in L} = \frac{100 \, \text{mL}}{1000} = 0.1 \, \text{L} \]

### Step 3: Calculate the molarity of the solution
Molarity (M) is defined as the number of moles of solute per liter of solution. The formula for molarity is:

\[ \text{Molarity (M)} = \frac{\text{Number of moles}}{\text{Volume of solution in L}} \]

Substituting the values we calculated:

\[ \text{Molarity} = \frac{0.1 \, \text{mol}}{0.1 \, \text{L}} = 1 \, \text{M} \]

### Final Answer
The molarity of the NaOH solution is **1 M**.

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