Question

A solution is prepared by adding 2 g of X” to 1 moIe of water. Mass percent of “X” in the solution is

• A. 20%
• B. 5%
• C. 10%
• D. 2%

Answer 1

The Correct Option is C

Given:

• Mass of solute (\( X \)) = 2 g
• Moles of solvent (\( \text{H}_2\text{O} \)) = 1 mole

Step 1: Calculate the Mass of the Solvent

The molar mass of water (\( \text{H}_2\text{O} \)) is 18 g/mol. Since we have 1 mole of water:

\[ \text{Mass of solvent} = 1 \, \text{mol} \times 18 \, \text{g/mol} = 18 \, \text{g}. \]

Step 2: Calculate the Total Mass of the Solution

The total mass of the solution is the sum of the mass of the solute and the mass of the solvent:

\[ \text{Total mass} = \text{Mass of solute} + \text{Mass of solvent} = 2 \, \text{g} + 18 \, \text{g} = 20 \, \text{g}. \]

Step 3: Calculate the Mass Percent of \( X \)

The mass percent of \( X \) is given by:

\[ \% \text{mass of } X = \frac{\text{Mass of } X}{\text{Total mass}} \times 100 = \frac{2 \, \text{g}}{20 \, \text{g}} \times 100 = 10\%. \]

Final Answer:

The mass percent of \( X \) in the solution is 10%.