The molarity of a solution containing `5.0g` of NaOH in 250 mL solution is :

Options

A. `0.1`
B. `0.5`
C. `1.0`
D. `2.0`

Answer

To find the molarity of a solution containing 5.0 g of NaOH in 250 mL of 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:

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

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

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

Now, substituting the values:

\[ \text{Number of moles of NaOH} = \frac{5.0 \, \text{g}}{40 \, \text{g/mol}} = 0.125 \, \text{moles} \]

### 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:

\[ \text{Volume (L)} = \frac{250 \, \text{mL}}{1000} = 0.250 \, \text{L} \]

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

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

Substituting the values we calculated:

\[ \text{Molarity (M)} = \frac{0.125 \, \text{moles}}{0.250 \, \text{L}} = 0.5 \, \text{M} \]

### Final Answer
The molarity of the solution is **0.5 M**.

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