Question

$300$ g of an aqueous solution of a particular solute (containing $30$% solute by mass) is mixed with $400$ g of another aqueous solution of the same solute (containing $40$% solute by mass). In the final solution, mass $\%$ of solute is :

[Given, Molecular mass of solute $=50$]

• A. $40.09\%$
• B. $39.87\%$
• C. $34.05\%$
• D. $35.71\%$

Answer 1

The correct option is D $35.71\%$

$300$ g of $30$% solution contain $300\times \frac{30}{100}=90$ g of solute.
$400$ g of $40$% solution contain $400\times \frac{40}{100}=160$ g of solute.
The mass percent of the final solution $=\frac{Massofsolute}{Massofsolution}=\frac{90+160}{300+400}\times 100=35.71\%$.