MHT CET · Chemistry · Solutions

Which of the following sets of solutions of urea $(m o l . m a s s 60 g m o l^{- 1})$ and sucrose $(m o l . m a s s 342 g m o l^{- 1})$ is isotonic?

A $9.1 g L^{- 1}$ urea and $6.0 g L^{- 1}$ sucrose
B $3.0 g L^{- 1}$ urea and $3.0 g L^{- 1}$ sucrose
C $6.0 g L^{- 1}$ urea and $9.0 g L^{- 1}$ sucrose
D $3.0 g L^{- 1}$ urea and $17.1 g L^{- 1}$ sucrose

Verified Solution

Answer & Solution

Correct Answer

(D) $3.0 g L^{- 1}$ urea and $17.1 g L^{- 1}$ sucrose

Step-by-step Solution

Detailed explanation

Key Idea Isotonic solutions are those solutions which have same osmotic pressure at a given temperature.
Formula for osmotic pressure,

π = C R T

Considering the set given in option

(d),

i.e.

3.0 g L^{- 1}

urea and 17.1

g L^{- 1}

sucrose. Given, molecular of sucrose 342

g m o l^{- 1} .

For urea,
Conc.C

= \frac{3}{60} = \frac{1}{20}

Osmotic pressure

π_{1} = \frac{1}{20} \times R \times T

For sucrose conc.

C = \frac{17.1}{342} = \frac{1}{20}

∴

Osmotic pressure,

π_{2} = \frac{1}{20} R T

Thus, set of solution of urea and sucrose given in option

(d)

is isotonic.

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

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Which of the following sets of solutions of urea mol.mass 60 g mol-1 and sucrose mol.mass 342 g mol-1 is isotonic?

Step-by-step Solution

Which of the following sets of solutions of urea $(m o l . m a s s 60 g m o l^{- 1})$ and sucrose $(m o l . m a s s 342 g m o l^{- 1})$ is isotonic?