Recall the definition of retardation factor , $R_f$

In chromatography, $R_f = \frac{\text{distance travelled by the compound (spot)}}{\text{distance travelled by the solvent front}}$

Check Statement I

Statement I says: $R_f$ can be measured in meter/centimeter.

Since $R_f$ is a ratio of two distances, its units cancel: $R_f = \frac{\text{cm}}{\text{cm}} = \text{unitless}$ or $R_f = \frac{\text{m}}{\text{m}} = \text{unitless}$

So, $R_f$ has no unit. It is a dimensionless quantity.

Therefore, Statement I is false.

Check Statement II

Statement II says: $R_f$ value of a compound remains constant in all solvents.

This is incorrect. The $R_f$ value depends on:

• the nature of the compound
• the stationary phase
• the solvent/mobile phase
• temperature and experimental conditions

So, changing the solvent generally changes the $R_f$ value.

Therefore, Statement II is false.

Choose the correct option

• Statement I: False
• Statement II: False

Hence, the correct option is: $\boxed{D}$

Compare with stored correct answer

Stored correct answer: D

My derived answer also is D, so they agree.