Question

200 g of 20\% w/w urea solution is mixed with 400 g of 40\% w/w urea solution. What is the weight percentage (w/w \%) of resultant solution?

• A. 30.33
• B. 33.33
• C. 36.33
• D. 28.33

Hint:

To solve such problems, always use the concept of mass balance, which helps in calculating the total weight of urea in a solution.

Answer 1

The Correct Option is B

Let’s calculate the weight percentage using the formula: \[ \text{Weight \% of urea} = \frac{\text{Weight of urea}}{\text{Total weight of solution}} \times 100 \] Weight of urea in 200 g of 20\% solution = \( \frac{20}{100} \times 200 = 40 \, g \).
Weight of urea in 400 g of 40\% solution = \( \frac{40}{100} \times 400 = 160 \, g \).
Total weight of urea = 40 + 160 = 200 g. Total weight of solution = 200 + 400 = 600 g. Thus, the weight percentage of urea in the resultant solution is: \[ \text{Weight \%} = \frac{200}{600} \times 100 = 33.33\% \]