JEE Main 2026 — Solutions Question with Solution

For osmotic pressure, using the van 't Hoff equation: $\pi =iMRT$.
The living cell has osmotic pressure of 12 atm.
For an isotonic NaCl solution, the osmotic pressures must be equal.
For NaCl solution: $\pi =i\times M\times R\times T$, where $i=2$ (complete dissociation into Na⁺ and Cl⁻).
$12=2\times M\times 0.08\times 300$
$12=48M$
$M=0.25$ mol/L
Molar mass of NaCl = 23 + 35.5 = 58.5 g/mol.
Concentration in g/L = $0.25\times 58.5=14.625\approx 15$ g/L