Question

Two elements A (At. mass - 75) and B (At. mass = 16) combine to yield a compound. The % by mass of A in the compound was found to be 75.08. The formula of the compound is:

• A. $A_2{B}_3$
• B. $AB$
• C. $A{B}_2$
• D. $A_2{B}_2$

Answer 1

The correct option is A $A_2{B}_3$

Element	%	Atomic mass	Relative no. of atoms	simplest ratio
$A$	75.8	75	75.8/75 = 1.01	1 x 2 = 2
$B$	24.2	16	24.2/16 = 1.51	1.5 x 2 = 3

$\therefore$ The formula is $A_2{B}_3$.

Hence, option $A$ is correct.