To carry out metabolism, oxygen is taken up by hemoglobin ($\mathrm{Hb}$) to form oxyhemoglobin (${\mathrm{HbO}}_2$ ) according to the elementary reaction :

$\mathrm{Hb}\left(\mathrm{aq}\right)+{\mathrm{O}}_2\left(\mathrm{aq}\right)\stackrel{\mathrm{K}}{⟶}{\mathrm{HbO}}_2\left(\mathrm{aq}\right)$

The value of K is $2.0\times {10}^6{\mathrm{M}}^{-1}{\mathrm{s}}^{-1}$ at $37° \mathrm{C}$(body temperatures). For an average adult, the concentrations of $\mathrm{Hb}$ and $O_2$ in the blood in the lungs are $8.0\times {10}^{-6}\mathrm{M}$ and $1.5\times {10}^{-6}\mathrm{M}$ , respectively. The rate of formation of ${\mathrm{HbO}}_2$ increases to $1.6\times {10}^{-4}{\mathrm{Ms}}^{-1}$ during an exercise to meet the demand of increased metabolism rate. Assuming the $\mathrm{Hb}$ concentration to remain same, what must the oxygen concentration be to sustain this rate of ${\mathrm{HbO}}_2$ formation?

[If the answer is 'X', then fill OMR by multiplying 'X' with ${10}^6$]