Question

Two elements X (at. mass 16) and Y (at.mass14) combine to form compounds A, B and C. The ratio of different masses of Y which combine with a fixed mass of X in A, B and C is 1 : 3 : 5. If 32 parts by mass of X combines with 84 parts by mass of Y in B, then in C, 16 parts by mass of X will combine with :

• A. 14 parts by mass of Y
• B. 42 parts by mass of Y
• C. 70 parts by mass of Y
• D. 84 parts by mass of Y

Answer 1

Answer: (C)

In $B$, $32$ parts of $X$ combines with $Y=84$ parts
$\therefore$ $16$ parts of $X$ will combine with $Y=42$ parts
Now number of parts of $X$ in both $B$ and $C$ is equal
Different masses of $Y$ which combine with a fixed mass of $X$ in $B$ and $C$ are in the ratio $3:5$
$\therefore$ $\frac{\text{Mass of Y in B}}{\text{Mass of Y in C}}=\frac{3}{5}$
$\frac{\text{42 parts}}{\text{Mass of Y in C}}=\frac{3}{5}$
$\therefore$ Mass of Y in C $=\frac{5}{3}\times 42$
$=70$ parts