On a thin layer chromatographic plate, an organic compound moved by $$3.5 \text{ cm}$$, while the solvent moved by $$5 \text{ cm}$$. The retardation factor of the organic compound is ____________ $$\times 10^{-1}$$.

The retardation factor ($$R_f$$) in thin layer chromatography is defined as:

$$ R_f = \frac{\text{Distance moved by compound}}{\text{Distance moved by solvent}} $$

Given:

Distance moved by compound = $$3.5$$ cm

Distance moved by solvent = $$5$$ cm

Substituting:

$$ R_f = \frac{3.5}{5} = 0.7 $$

Expressing in the required form:

$$ R_f = 7 \times 10^{-1} $$

Therefore, the answer is $$\boxed{7}$$.