Question

If the mole fraction of sodium is 0.25 in 9 moles of liquid carbon dioxide, what is the mass fraction of sodium?

(a) 0.10

(b) 0.15

(c) 0.20

(d) 0.25

This question was addressed to me in an interview.

My query is from Mole Fraction and Mass(Weight) Fraction in chapter Moles, Density & Concentration of Basic Chemical Engineering

Answer 1

Correct option is (b) 0.15

The explanation: 0.25 = n/(n + 9), => n = 3, => mass of sodium = 3*23/(3*23 + 9*44) = 0.15.