Verified Solution • 2025–26 Session moderate

QJEEM20Ch3c1a: JEE Main 2020 Chemistry - Class 12 JEEM20Ch3c1a Solution: If 250 cm 3 of an aqueous solution containing 0.73 g of a…

If 250 cm3 of an aqueous solution containing 0.73 g of a protein A is isotonic with one litre of another aqueous solution containing 1.65 g of a protein B, at 298 K, the ratio of the molecular masses of A and B is ______ × 10–2 (to the nearest integer).

Step-by-Step Verified Solution

Let molar mass of protein A = x g/mol

Let molar mass of protein B = y g/mol

π\pi A = osmotic pressure of protein A = 0.73x×1000250×RT{{0.73} \over x} \times {{1000} \over {250}} \times RT

π\pi B = osmotic pressure of protein B = 1.65y×11×RT{{1.65} \over y} \times {1 \over 1} \times RT

Given π\pi A = π\pi B

⇒\Rightarrow 0.73x×1000250×RT{{0.73} \over x} \times {{1000} \over {250}} \times RT = 1.65y×11×RT{{1.65} \over y} \times {1 \over 1} \times RT

⇒\Rightarrow xy{x \over y} = 0.730.25×1.65{{0.73} \over {0.25 \times 1.65}} = 1.77

= 177 ×\times 10-2

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