Answer: The [tex]R_f[/tex] value is 0.664
Explanation:
Distance travelled by solvent front = (7.7-1.45)cm = 6.25 cm
Distance travelled by unknown = (5.6-1.45) cm = 4.15 cm
The retention factor or the [tex]R_f[/tex] value is defined as the ratio of distance traveled by the unknown to the distance traveled by the solvent front.
[tex]R_f=\frac{\text {distance travelled by unknown}}{\text {distance travelled by solvent}}[/tex]
[tex]R_f=\frac{4.15}{6.25}=0.664[/tex]
Thus the [tex]R_f[/tex] value is 0.664