A solution is prepared by dissolving 10 g of NaOH in 100 mL of solution. Its molarity is

Options

A. 1.0 M
B. 2.5 M
C. 1.5 M
D. 4.0 M

Explanation

To find the molarity of the solution prepared by dissolving 10 g of NaOH in 100 mL of solution, we can follow these steps:

### Step 1: Calculate the number of moles of NaOH
To find 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

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

Now, substituting the values:

\[ \text{Number of moles of NaOH} = \frac{10 \text{ g}}{40 \text{ g/mol}} = 0.25 \text{ moles} \]

### Step 2: Convert the volume of the solution from mL to L
The volume of the solution is given as 100 mL. To convert this to liters, we use the conversion:

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

So,

\[ \text{Volume (L)} = \frac{100 \text{ mL}}{1000} = 0.1 \text{ L} \]

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

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

Substituting the values we calculated:

\[ \text{Molarity (M)} = \frac{0.25 \text{ moles}}{0.1 \text{ L}} = 2.5 \text{ M} \]

### Final Answer
The molarity of the solution is **2.5 M**.

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