The number of moles of the solute present in 500 ml of 0.04 M solution is:

Explanation

To find the number of moles of solute present in a 500 ml of 0.04 M solution, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Definition of Molarity**:
Molarity (M) is defined as the number of moles of solute per liter of solution. The formula is:
\[ \text{Molarity (M)} = \frac{\text{Number of moles of solute}}{\text{Volume of solution in liters}} \]

2. **Convert Volume from ml to Liters**:
Since the volume is given in milliliters (ml), we need to convert it to liters.
\[ 500 \, \text{ml} = 500 \times 10^{-3} \, \text{liters} = 0.5 \, \text{liters} \]

3. **Use the Molarity Formula to Find Number of Moles**:
Rearranging the molarity formula to find the number of moles gives us:
\[ \text{Number of moles} = \text{Molarity} \times \text{Volume in liters} \]
Substituting the values we have:
\[ \text{Number of moles} = 0.04 \, \text{M} \times 0.5 \, \text{liters} \]

4. **Calculate the Number of Moles**:
Now, perform the multiplication:
\[ \text{Number of moles} = 0.04 \times 0.5 = 0.02 \, \text{moles} \]

### Final Answer:
The number of moles of solute present in 500 ml of 0.04 M solution is **0.02 moles**.