Decreasing order of osmotic pressure for 0.01 M aqueous solutions of

barium chloride, potassium chloride, acetic acid and sucrose isBaCl2 KCl CH3COOH sucrose.EXPLAIN IN DETAIL .

We have the formula for osmotic pressure as:
$\mathrm{\pi }=\mathrm{iMRT}$
Where, i = van't hoff factor, M = molar concentration.
Since, M, R and T are constant for the three compounds so the value of osmotic pressure depends on "i".
Formula of i is given as

$i = \frac{\text{Total number of ions after dissociation/association}}{\text{Total number of ions before dissociation /association}}$

BaCl₂ → Ba²⁺  +  2Cl^-

KCl  → K⁺  +  Cl^-

For BaCl_​2, i = 3(three ions)
For KCl, i = 2
Acetic acid does not dissociate completely. The value of "i" depend on the degree of dissociation. But "i" will be greater than 1. 
Sucrose, C₁₂H₂₂O₁₁ does not undergo dissociation / association. So, "i" will be 1.

Hence, the osmotic pressure in decreasing order as:
BaCl₂> KCl>_​​CH₃COOH​> C₁₂H₂₂O₁₁