MCQEasyJEE 2023Concentration Terms (Molarity, Molality, etc.)

JEE Chemistry 2023 Question with Solution

A solution of sugar is obtained by mixing 200g200 \, \text{g} of its 25%25\% solution and 500g500 \, \text{g} of its 40%40\% solution (both by mass). The mass percentage of the resulting sugar solution is _____ (Nearest integer)

  • A

    3535

  • B

    3636

  • C

    3737

  • D

    3838

Answer

Correct answer:B

Step-by-step solution

Standard Method

Given:

  • Solution (I): mass of solution = 200g200 \, \text{g}, sugar percentage = 25%25\%
  • Solution (II): mass of solution = 500g500 \, \text{g}, sugar percentage = 40%40\%

Find: The mass percentage of sugar in the resulting mixed solution.

Mass of sugar in solution (I):

25100×200=50g\frac{25}{100} \times 200 = 50 \, \text{g}

Mass of sugar in solution (II):

40100×500=200g\frac{40}{100} \times 500 = 200 \, \text{g}

Total mass of solution:

200+500=700g200 + 500 = 700 \, \text{g}

Total mass of sugar:

50+200=250g50 + 200 = 250 \, \text{g}

Now, the final percentage of sugar is:

250700×100=35.7136\frac{250}{700} \times 100 = 35.71 \approx 36

Therefore, the mass percentage of the resulting sugar solution is 36%36\%. The correct option is B.

Common mistakes

  • Using 25%25\% and 40%40\% directly to average the percentages is incorrect because the two solutions have different masses. First find the actual mass of sugar in each solution, then divide by the total mass.

  • Treating 200g200 \, \text{g} and 500g500 \, \text{g} as masses of sugar is wrong. They are masses of the solutions, so the sugar mass must be calculated using the given percentages.

  • Forgetting to use the total mass of the mixed solution, 700g700 \, \text{g}, in the denominator gives an incorrect percentage. Always divide total solute mass by total solution mass.

Practice more Concentration Terms (Molarity, Molality, etc.) questions

Get unlimited AI-adaptive practice, mastery tracking, and an AI tutor that explains every step — free to start.

Related questions