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 g.

In the formation of X, 4 g of A combine with 12 g of B.

Thus in the formation of Y, 4 g of A combine with 28 g of B.
(According to the mass ratio given)

Hence in the formation of Y, 8 g of A will combine with
$=\frac{28}{4}\times 8g=56g$