Question

Some faculty members of XYZ classes were trying to simplify a problem for students by mentioning data explicity about a gaseous mixture. Information given by them is as follow.
Faculty - 1 : Mixture consist of three gases A, B and C.
Faculty - 2 : Molar mass of B is twice of A & Molar mass of A is $4$ times of C.
Faculty 3 : The gas that is neither heaviest nor lightest is $16\%$ by mass.
Faculty - 4 : Molar ratio of heaviest to lightest gas is $2:5$
Based on the above information, answer the question that follows.
What is the molar ratio of A : B :C?

• A. $5:2:2$
• B. $2:2:5$
• C. $2:1:5$
• D. $1:2:5$

Answer 1

The correct option is D $1:2:5$

Given that

$A=4C$

$B=2A$

$\therefore B=8C$

Given that $\frac{B}{C}=\frac{2}{5}$

If $B=2,A=1$

$\therefore$ The molar ratio of $A:B:C=1:2:5$