Question

A $10\%$ solution is one in which 10 gm of solute is dissolved in 100 gm of water. On heating the solution water evaporates. So, 1 kg of the $10\%$ solution is reduced to 0.4 kg. What is its concentration now?

• A. 32.6%
• B. 14.8%
• C. 22.7%
• D. 29.4%

Answer 1

The correct option is D 29.4%

In a $10\%$ solution, in 110 gm of solution there is 10gm of solute.

So, 1 kg of solution has $1\times \frac{10}{110}=\frac{1}{11}$ kg of solute.

After heating, amount of solution = 0.4 kg

So, amount of water $=\frac{2}{5}-\frac{1}{11}=\frac{17}{55}$ kg

Solution percentage $=\left(\frac{1}{11}\right)\times \left(\frac{55}{17}\right)\times 100=29.4\%$