Q151 · CSIR-NET Chemistry, December 2019

Paper: CSIR-NET December 2019 · Subject: Physical Chemistry · Chapter: Surface Chemistry · Topic: Adsorption Isotherms · Marks: 2 · Difficulty: Medium

A gas is known to satisfy Langmuir isotherm when adsorbed on a certain metal surface. If the fractional coverage of the gas is 0.5 when the gas pressure is 1.0 Pa , the fractional coverage at 3.0 Pa would be closest to
(a)0.67
(b)0.75
(c)0.80
(d)1.0
Answer
Answer: B ✓ checked by 4AB · confidence high

The source book printed D; on checking, B is correct — see the explanation.

Explanation
θ = 0.5 at 1 Pa gives K = 1 Pa⁻¹; at 3 Pa θ = 3/(1 + 3) = 0.75.

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