Question

A$10\%$salt solution means that

• A. $10\mathrm{gm}$ of salt is present in $100\mathrm{gm}$ of water
• B. $10\mathrm{gm}$ of salt is present in $90\mathrm{gm}$ of water

Answer 1

The correct option is B

$10\mathrm{gm}$ of salt is present in $90\mathrm{gm}$ of water

Mass percentage: The mass percentage is the mass of solute per $100$ mass unit of solution.

The concentration of the salt solution is given as $10\%$.

Explanation for correct option:

(b) $10\mathrm{gm}$ of salt is present in $90\mathrm{gm}$ of water:

1. $10\%$of salt solution means $10\mathrm{gm}$ of salt dissolved in $100\mathrm{gm}$ of solution.
2. $\mathrm{Mass}\mathrm{of}\mathrm{solution}=\mathrm{Mass}\mathrm{of}\mathrm{solute}+\mathrm{Mass}\mathrm{of}\mathrm{solvent}$.
3. On adding $10\mathrm{gm}$ in $90\mathrm{gm}$ of water the mass of the solution becomes $100\mathrm{gm}$.
4. It means that the solvent should be $90\mathrm{gm}$.

Explanation for incorrect options:

(a) $10\mathrm{gm}$ of salt is present in $100\mathrm{gm}$ of water:

1. On adding $10\mathrm{gm}$ in $100\mathrm{gm}$ of water the mass of the solution becomes $110\mathrm{gm}$.
2. The concentration of the solution will be less than $10\%$.

Hence, option (a) is the correct option.