The solution of sugar in water contains

The oxygen dissolved in water exerts a partial pressure of $20 \ kPa$ in the vapour above water. The molar solubility of oxygen in water is ............ $\times 10^{-5} \ mol \ dm^{-3}$ (Round off to the Nearest Integer). [Given: Henry's law constant $K_H = 8.0 \times 10^{4} \ kPa$ for $O_2$,Density of water $= 1.0 \ kg \ dm^{-3}$]

The solubility of $N_2$ gas in water at $25 \text{ }^\circ\text{C}$ and $1 \text{ bar}$ is $6.85 \times 10^{-4} \text{ mol L}^{-1}$. Calculate the solubility of $N_2$ gas in water at the same temperature when the partial pressure of $N_2$ is $0.70 \text{ bar}$.

$A$ gas $X$ is dissolved in water at $2 \ bar$ pressure. Its mole fraction in the solution is $0.02$. Find the mole fraction of water in the solution when the pressure of the gas is doubled at the same temperature.

$CO_2$ gas is bubbled through water during a soft drink manufacturing process at $298 \ K$. If $CO_2$ exerts a partial pressure of $0.835 \ bar$,then $x \ mmol$ of $CO_2$ would dissolve in $0.9 \ L$ of water. The value of $x$ is $.....$ (Nearest integer).
(Henry's law constant for $CO_2$ at $298 \ K$ is $1.67 \times 10^3 \ bar$)

$5.5 \text{ mg}$ of nitrogen gas dissolves in $180 \text{ g}$ of water at $273 \text{ K}$ and $1 \text{ atm}$ pressure due to nitrogen gas. The mole fraction of nitrogen in $180 \text{ g}$ of water at $5 \text{ atm}$ nitrogen pressure is approximately: