Consider the following pairs of solution which will be isotonic at...

A solution having the same solute and solvent concentration as a cell across the semipermeable membrane is referred to as isotonic solution.

The effective concentration of each solution can be calculated as follows,

Effective concentration $= i ( {Von}^{'}tHofffactor ) \times C$

$1MNaCl$ has effective concentration $= 2 \times 1 = 2M$ and hence it is isotonic with two molar urea solution.

$1M{CaCl}_{2}$ has effective concentration $= 3Mand1 . 5MKCl$ has also $3M$, hence, both are isotonic.

$1 . 5M{AlCl}_{3} ≅ 6Mand2M{Na}_{2}{SO}_{4} ≅ 6M$, Hence both are isotonic.

$2 . 5MKCl ≅ 5Mand1M{Al}_{2}{\left({SO}_{4}\right)}_{3} ≅ 5M$, Hence both are isotonic.