Question

An aqueous solution of which of the following compounds shows abnormal osmotic pressure?

• A. Urea
• B. Common salt
• C. Glucose
• D. Sucrose

Hint:

Electrolytes like NaCl dissociate into multiple ions, leading to higher osmotic pressure compared to non-electrolytes like urea, glucose, and sucrose.

Answer 1

The Correct Option is B

Step 1: Understand osmotic pressure.
Osmotic pressure is the pressure exerted by a solution to prevent the flow of solvent into it through a semipermeable membrane. It depends on the concentration of solute particles in the solution.
Step 2: Analyze the compounds.
- Urea, glucose, and sucrose are non-electrolytes. They do not dissociate into ions and therefore contribute only one particle each in the solution. - Common salt (NaCl) dissociates into two ions (Na$^+$ and Cl$^-$), so it contributes two particles per formula unit, which leads to a higher osmotic pressure than the non-electrolytes.
Step 3: Apply to the options.
Since common salt dissociates into two ions, it will show abnormal osmotic pressure compared to the other non-electrolytes.
Final Answer: \[ \boxed{\text{Common salt}} \]