Question 85

The w/v percentage strength of the urea solution is 15%.

To calculate the w/v percentage strength, we use the formula: (mass of solute in grams/volume of solution in mL) × 100. In this case, (12 g / 80 mL) × 100 equals 15%.

A) 6.60%

This option is incorrect. A w/v percentage of 6.60% would imply that there are only 5.28 grams of urea in 80 mL of solution, which does not match the given data of 12 grams.

B) 9.60%

This option is also incorrect. A w/v percentage of 9.60% would suggest that there are approximately 7.68 grams of urea in 80 mL, which is significantly less than the actual 12 grams present in the solution.

C) 15%

This option is correct. The calculation of the w/v percentage strength confirms that (12 g / 80 mL) × 100 results in 15%, accurately reflecting the concentration of urea in the solution.

D) 150%

This option is incorrect as well. A w/v percentage of 150% would imply an unrealistic scenario where the mass of urea exceeds the volume of the solution, which is impossible in a standard concentration calculation.

Conclusion

The correct answer of 15% w/v strength accurately reflects the concentration of urea in the solution based on the provided mass and volume. All other options fail to represent the correct calculation, either underestimating or overestimating the concentration, which confirms the accuracy of the chosen answer.