The surface tension ($\gamma$) of a solution, prepared by mixing 0.02 mol of an organic acid in 1 L of pure water, is represented as
\[
\gamma^* - \gamma = A \log(1 + Bc)
\]
where $\gamma^*$ is the surface tension of pure water,
$A = 0.03 \, \mathrm{N\,m^{-1}}$, $B = 50 \, \mathrm{mol^{-1}\,L}$, and $c$ is concentration in mol L$^{-1}$.
The excess concentration of the organic acid at the surface of the liquid, determined by Gibbs adsorption equation at 300 K, is $n \times 10^{-6} \, \mathrm{mol\,m^{-2}}$.
The value of $n$ (rounded off to two decimal places) is ________.
