A flask (100 ml volume) has wastewater, which has $0.12 \mathrm{mg} / \mathrm{L}$ geosmin. Activated carbon is added in this flask for adsorbing geosmin as per the Freundlich isotherm model $\left(\mathrm{Q}=2.6 \times \mathrm{C}^{0.73}\right.$ where $\mathrm{Q}$ is $\mathrm{mg}$ adsorbate $/ \mathrm{mg}$ adsorbent and $\mathrm{C}$ is the equilibrium concentration in $\mathrm{mg} / \mathrm{L}$ ). Activated carbon to be added in this flask for getting final remaining geosmin concentration of $0.05 \mathrm{mg} / \mathrm{L}$ would be __________ (in $\mathrm{mg} / \mathrm{L}$, $\text{rounded off to three decimal places).}$
