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JEE Advanced levelOne or more correct optionsDifficulty 3 of 3si107

For a TLC experiment, which statements are correct?

AThe $R_{f}$ value of a compound cannot be greater than 1.
BThe $R_{f}$ value of a given compound is the same in all solvent systems.
CSpots at $1.8 cm$ and $4.2 cm$ with the solvent front at $6.0 cm$ have $R_{f}$ values $0.30$ and $0.70$ .
DOn silica gel the spot with $R_{f} = 0.30$ corresponds to the less strongly adsorbed compound compared with the spot of $R_{f} = 0.70$ .

Answer: A, C

The solute cannot travel farther than the solvent front, so

R_{f} \leq 1

.

1.8/6.0 = 0.30

and

4.2/6.0 = 0.70

.

R_{f}

depends on solvent and adsorbent, and the lower

R_{f}

shows stronger adsorption, so statements 2 and 4 are wrong.

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