The Henry’s law constant for the solubility of $N_2$  gas in water at 298K is ${10}^5$ atm. The mole fraction of $N_2$  in air is 0.8. The number of moles of $N_2$  from air dissolved in 10 moles of water at 298K and 5atm pressure is  $y\times {10}^{-5}$. What is ‘y’?