Question

A 6% solution of urea is isotonic with

• A. 1 M solution of glucose
• B. 0.05 M solution of glucose
• C. 6% solution of glucose
• D. 25% solution of glucose

Hint:

Isotonic solutions have equal molarities ($\pi_1 = \pi_2 \Rightarrow C_1 = C_2$).

Answer 1

The Correct Option is A

Step 1: Calculate Molarity of Urea
6% solution means 6g in 100mL. Molecular weight of urea is 60.
Molarity $= \frac{6/60}{100/1000} = \frac{0.1}{0.1} = 1$ M.
Step 2: Isotonic Condition
Solutions are isotonic if they have the same molar concentration (osmotic pressure).
Step 3: Conclusion
Since the urea solution is 1 M, it is isotonic with a 1 M solution of glucose.
Final Answer: (a)