Question

Molar ratio of $N{a}_{2}S{O}_3$ and $H_{2}O$ is $1:7$ in $N{a}_{2}S{O}_3\cdot x{H}_{2}O$. Hence, mass percentage is :

• A. $12.5:87.5$
• B. $87.5:12.5$
• C. $50:50$
• D. $75:25$

Answer 1

The correct option is C $50:50$

As molar ratio of $N{a}_{2}S{O}_3$ and $H_{2}O$ is $1:7$ in $N{a}_{2}S{O}_3\cdot 7H_{2}O$.
The molecular mass of $N{a}_{2}S{O}_3=126$ g/mol
The mass of $7$ molecules of $H_{2}O=126$ g
Hence. mass % is $126:126=50:50$