Place the following solutions in order of increasing osmotic pressure. i. 0.15 m c2h6o2. ii. 0.15 m mgcl2, iii. 0.15 m nacl, a. iii < i < ii b. ii < iii < i c. i < ii < iii d. i < iii < ii the answer is d but how do you know?

D. I < III < II

Explanation:

π = iMRT.

where, π is the osmotic pressure.

i is van 't Hoff factor.

M is the molarity of the solution.

R is the general gas constant.

T is the temperature.

M, R and T are constant for all solutions.

So, the osmotic pressure depends on the van 't Hoff factor.

For C₂H₆O₂ (non-electrolyte solute): i = 1.

For MgCl₂: i = 3.

It dissociates to give (Mg²⁺ + 2Cl⁻).

For NaCl: i = 2.

It dissociates to give (Na⁺ + Cl⁻).

So, the solute that has the highest osmotic pressure is  II. 0.15 M MgCl₂, then III. 0.15 M NaCl, then I. 0.15 M C₂H₆O₂.

D. I < III < II.