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ChemistryInteger+4 / -1Question 73 of 75

JEE Main 2026 · 5 Apr · Shift 2, Chemistry question 73

20 g hemoglobin in a 1 L aqueous solution (A) at 300 K is separated from pure water by semi permeable membrane. At equilibrium the height of solution in a tube dipped in a solution (A) is found to be 80.0 mm higher than the tube dipped in water.

The molar mass of hemoglobin is ________ kg mol−1^{-1}. (Nearest integer)

(Given : g=10g=10 m s−2^{-2}, R=8.3R=8.3 kPa dm³ K−1^{-1}mol−1^{-1}, density of solution = 1000 kg m−3^{-3})

Answer and worked solution

Official answer: 62

Osmotic pressure from the column height.
π=hρg=0.080×1000×10=800 Pa=0.8 kPa.\pi=h\rho g=0.080\times1000\times10=800\text{ Pa}=0.8\text{ kPa}.

Concentration.
C=πRT=0.88.3×300=3.21×10−4 mol dm−3.C=\frac\pi{RT}=\frac{0.8}{8.3\times300}=3.21\times10^{-4}\text{ mol dm}^{-3}.

Molar mass. 203.21×10−4≈62 250\dfrac{20}{3.21\times10^{-4}}\approx62\,250 g mol−1≈62^{-1}\approx62 kg mol−1^{-1}.

Answer: 62

Topics:Colligative properties
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