Consider separate solutions of `0.500 M C_(2)H_(5)OH(aq)`,`0.100 M Mg_(3)(PO_(4))(aq)`,`0.250 M KBr(aq)`, and `0.125 M Na_(3)PO_(4)(aq)` at `25^(@)C`. Which statement is true about these solutions, assuming all salts to be strong electrolytes?

Options

A. `0.125 M Na_(3)PO_(4)(aq)` has the highest osmotic pressure.
B. `0.500 M C_(2)H_(5)OH` has the highest osmotic pressure.
C. They all have the same osmotic pressure.
D. `0.100 M Mg_(3)(PO_(4))_(2)(aq)` has the highest osmotic pressure.

Answer

C

Explanation

For `C_(2)H_(5)OH`, `pi=1 xx 0.5 xx RT =0.5 RT`
For `KBr`, `pi=2 xx 0.25 xx RT =0.5 RT`
For `Mg_(3)(PO_(4))_(2)`, `pi=5 xx 0.1 xx RT =0.5 RT`
For `Na_(3)PO_(4)`, `pi=4 xx 0.125 xx RT =0.5 RT`
So, all are isotonic solutions.