Question

A compound contains equal masses of the element A, B and C. The atomic mass of A, B and C are 20 u, 40 u and 60 u respectively. The empirical formula of the compound is:

• A. $A_3{B}_{2}C$
• B. $A{B}_2{C}_3$
• C. $ABC$
• D. $A_6{B}_3{C}_2$

Answer 1

The correct option is D $A_6{B}_3{C}_2$

Let mass of A, B and C be W and $N_A$, $N_B$ and $N_C$ be moles of $A$, $B$ and $C$, then
$\therefore N_A:N_B:N_C=\frac{W}{20}:\frac{W}{40}:\frac{W}{60}=3:1.5:1\equiv 6:3:2$
So, the empirical formula is $A_6{B}_3{C}_2$