Question

Which of the following 0.1 M aqueous soloutions will exert highest osmotic pressure

Answer 1

you forgot the options . Options are :
(A) Al₂(SO₄)₃ , (B) Na₂SO₄ , (C) MgCl₂ ( D) KCl

(A) Al₂(SO₄)₃

Exaplantion :- as you know,
π = iCRT
where , π is osmotic pressure , i is van't Hoff' factor, R is universal gas constant and T is temperature of solution .
Here you can see that, osmotic pressure is directly proportional to van't Hoff' factor .
For Al₂(SO₄)₃ ⇔2Al³⁺ + 3SO₄²⁻
1 - α , 2α, 3α

i = 1 - α + 2α + 3α = 1 + 4α

Similarly for Na₂SO₄ ,MgCl₂, i = 1 -α + 2α + α = 1 + 2α
and KCl , i = 1 -α + α + α = 1 + α

What you observed ? i for Al₂(SO₄)₃ is largest that's why osmotic pressure is highest for it