18% (w/V) solution of urea (Mol. Mass=60) is

Options

A. 1 M
B. 2 M
C. 0.3 M
D. 3 M

Answer

To find the molarity of an 18% (w/V) solution of urea, we can follow these steps:

### Step 1: Understand the given information
We have an 18% (w/V) solution of urea, which means there are 18 grams of urea in 100 mL of solution. The molar mass of urea is given as 60 g/mol.

### Step 2: Calculate the number of moles of urea
To find the number of moles of urea, we use the formula:
\[ \text{Number of moles} = \frac{\text{mass of solute (g)}}{\text{molar mass (g/mol)}} \]
Substituting the values:
\[ \text{Number of moles of urea} = \frac{18 \, \text{g}}{60 \, \text{g/mol}} = 0.3 \, \text{moles} \]

### Step 3: Convert the volume of the solution to liters
The volume of the solution is given as 100 mL. To convert this to liters, we use the conversion factor:
\[ 1 \, \text{L} = 1000 \, \text{mL} \]
So,
\[ \text{Volume in liters} = \frac{100 \, \text{mL}}{1000} = 0.1 \, \text{L} \]

### Step 4: Calculate the molarity of the solution
Molarity (M) is defined as the number of moles of solute per liter of solution:
\[ \text{Molarity} = \frac{\text{Number of moles of solute}}{\text{Volume of solution in liters}} \]
Substituting the values we calculated:
\[ \text{Molarity} = \frac{0.3 \, \text{moles}}{0.1 \, \text{L}} = 3 \, \text{M} \]

### Conclusion
The molarity of the 18% (w/V) solution of urea is **3 M**.

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