Step 1: Understanding the Concept:
This is a straightforward calculation based on the definition of molarity. Molarity (M) is a unit of concentration, defined as the number of moles of solute per liter of solution.
Step 2: Key Formula or Approach:
The formula for molarity is:
\[ \text{Molarity (M)} = \frac{\text{moles of solute (n)}}{\text{Volume of solution in liters (V)}} \]
We can rearrange this formula to solve for the number of moles:
\[ n = M \times V \]
Step 3: Detailed Explanation:
Given:
- Molarity of the urea solution, M = 0.2 mol/L.
- Volume of the solution = 250 ml.
First, we must convert the volume from milliliters (ml) to liters (L):
\[ V = 250 \text{ ml} \times \frac{1 \text{ L}}{1000 \text{ ml}} = 0.250 \text{ L} \]
Now, use the rearranged formula to calculate the number of moles (n):
\[ n = M \times V \]
\[ n = 0.2 \frac{\text{mol}}{\text{L}} \times 0.250 \text{ L} \]
\[ n = 0.05 \text{ mol} \]
Step 4: Final Answer:
There are 0.05 moles of urea present in the solution. Therefore, option (C) is correct.