What will be the molarity of a solution containing `5`g of sodium hydroxide in`250ml` solution?

Options

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

Explanation

To find the molarity of a solution containing 5 g of sodium hydroxide (NaOH) in 250 ml of solution, we can follow these steps:

### Step 1: Calculate the number of moles of sodium hydroxide (NaOH).
To find the number of moles, we use the formula:

\[ \text{Moles} = \frac{\text{mass (g)}}{\text{molar mass (g/mol)}} \]

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

Adding these together gives:

\[ \text{Molar mass of NaOH} = 23 + 16 + 1 = 40 \text{ g/mol} \]

Now, we can calculate the moles of NaOH:

\[ \text{Moles of NaOH} = \frac{5 \text{ g}}{40 \text{ g/mol}} = 0.125 \text{ moles} \]

### Step 2: Convert the volume of the solution from milliliters to liters.
Since molarity is expressed in moles per liter, we need to convert 250 ml to liters:

\[ \text{Volume in liters} = \frac{250 \text{ ml}}{1000} = 0.250 \text{ L} \]

### Step 3: Calculate the molarity of the solution.
Now we can use the formula for molarity:

\[ \text{Molarity (M)} = \frac{\text{moles of solute}}{\text{volume of solution in liters}} \]

Substituting the values we have:

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

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

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