Question

Two elements A and B combine to form compounds X and Y. For a fixed mass of A, the mass of B that combines to form the compounds X and Y are in the ratio $3:7$. If in the compound X, $4\text{g}$ of A combines with $12\text{g}$ of B, then in compound Y, $8\text{g}$ of A will combine with _______ $\text{g}$ of B.

• A. $24$
• B. $56$
• C. $28$
• D. $8$

Answer 1

The correct option is B $56$

Given,
For the fixed mass of A, the mass of B that combines to form the compounds X and Y are in the ratio $3:7$.
Let the fixed mass of A in the compound X and Y be $4\text{g}$.
In the formation of X, $4\text{g}$ of A combine with $12\text{g}$ of B.
Thus in the formation of Y, $4\text{g}$ of A combine with $28\text{g}$ of B.
(According to the mass ratio given)
Hence in the formation of Y, $8\text{g}$ of A will combine with
$=\frac{28}{4}\times 8\text{g}=56\text{g}$