JEE Main · 2019 · 10 Apr 2019 · Shift 2 · Practical and Analytical Chemistry

In chromatography, which of the following statements is INCORRECT for

R_{f}

(A) $R_{f}$ value depends on the type of chromatography.
(B)The value of $R_{f}$ can not be more than one.
(C)Higher $R_{f}$ value means higher adsorption.✓ Correct
(D) $R_{f}$ value is dependent on the mobile phase.

Answer: (C)

Solution

The

R_{f}

value is the distance moved by the spot divided by the distance moved by the solvent front, so it genuinely depends on the kind of chromatography and on the mobile phase, and it can never exceed one because a spot cannot outrun the solvent. The claim that trips up is the one linking a high

R_{f}

to high adsorption - in fact a high

R_{f}

means the substance travelled far with the mobile phase, which signals weak adsorption on the stationary phase, not strong.

JEE Main · 2019 · 10 Apr 2019 · Shift 2 · Single correct option

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JEE Main · 2019 · 10 Apr 2019 · Shift 2 · Practical and Analytical Chemistry

Solution

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