The separation of two coloured substances was done by paper chromatography. The distances travelled by solvent front, substance $\mathrm{A}$ and substance $\mathrm{B}$ from the base line are $3.25 \mathrm{cm}.2.08 \mathrm{cm}$ and $1.05 \mathrm{cm}$. respectively. The ratio of ${\mathrm{R}}_{\mathrm{f}}$ values of $\mathrm{A}$ to $\mathrm{B}$ is (Answer the nearest integer)

Partition chromatography is based on continuous differential partitioning of components of a mixture between stationary and mobile phases. Paper chromatography is a type of partition chromatography. In paper chromatography, a special quality paper known as chromatography paper is used. Chromatography paper contains water trapped in it, which acts as the stationary phase.

The relative partition of each component of the mixture is expressed in terms of its retardation factor i.e. R_f value

R_f = $\frac{\mathrm{distance} \mathrm{travel} \mathrm{by} \mathrm{the} \mathrm{solute} \mathrm{from} \mathrm{the} \mathrm{base} \mathrm{line} }{\mathrm{distance} \mathrm{travel} \mathrm{by} \mathrm{the} \mathrm{solvent} \mathrm{from} \mathrm{the} \mathrm{base} \mathrm{line}}$

$\frac{{\mathrm{R}}_{{\mathrm{f}}_{\mathrm{A}}}}{{\mathrm{R}}_{{\mathrm{f}}_{\mathrm{H}}}}=\frac{\frac{2.08}{3.25}}{\frac{1.05}{3.25}}=\frac{2.08}{1.05}\simeq 2$