Question

3.1 g of a compound, “X” (molar mass = 62 g mol\(^{-1}\)) is dissolved in 19.5 g of another compound, Y (molar mass = 78 g mol\(^{-1}\)). The ratio of mole fractions of X and Y in the solution is:

• A. 1:5
• B. 5:1
• C. 4:1
• D. 1:4

Hint:

Mole fraction ratio = moles of X / moles of Y. Always convert mass to moles using molar mass.

Answer 1

The Correct Option is A

Step 1: Find moles of each component.
\(n_X = \frac{3.1}{62} = 0.05\) mol; \(n_Y = \frac{19.5}{78} = 0.25\) mol.

Step 2: Calculate mole fraction ratio.
\(\chi_X : \chi_Y = 0.05 : 0.25 = 1 : 5\).
\[ \boxed{1:5} \]