Question

How many g of $KCl$ would have to be dissolved in $60$ g $H_{2}O$ to give $20\%$ by mass of solution?

• A. $15$ g
• B. $1.5$ g
• C. $11.5$ g
• D. $31.5$ g

Answer 1

The correct option is A $15$ g

As we know,
$\%$ by mass $=\frac{\text{Mass of solute}}{\text{Mass of solution}}\times 100$
$20=\frac{\text{Mass of KCl}\times 100}{\text{Mass of KCl + Mass of water}}$
Let, $x$ be the mass of KCl

$20=\frac{100x}{x+60}$

$x=15g$

Therefore, mass of $KCl$ $=15$ g

Hence, the correct option is $A$