Verified Solution • 2025–26 Session
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QJEEM20Ch0d23: JEE Main 2020 Chemistry - Class 11 JEEM20Ch0d23 Solution: A chromatography column, packed with silica gel as stationary…
A chromatography column, packed with silica gel as stationary phase, was used to separate a mixture of compounds consisting of (A) benzanilide (B) aniline and (C) acetophenone. When the column is eluted with a mixture of solvents, hexane : ethylacelate (20:80), the sequence of obtained compounds is :
Multiple Choice Options
- A (A), (B) and (C)
- B (B), (A) and (C)
- C (C), (A) and (B)
- D (B), (C) and (A)
Step-by-Step Verified Solution
In column chromatography, we separate different parts of a mixture by washing it with solvents. The part of the mixture that gets most strongly attached to the moving solvent (or mobile phase) moves down the column quicker and comes out first. This is marked by a high Rf value. Other parts of the mixture follow in the order of decreasing Rf values.
In this particular separation, we're using a very polar solvent because most of it is ethyl acetate (80%). This means that the most polar part of the mixture (the one with the highest dipole moment) will have the highest Rf value and will be the first to come out. We measure the dipole moments of the mixture's components to determine this order.
The sequence of obtained compounds is
(C)>(A)>(B)