Which of the following ionic solids exhibits a decrease in its solubility in water with an increase in temperature?

The Henry's law constant for the solubility of $N_2$ gas in water at $298 \ K$ is $1.0 \times 10^5 \ atm$. 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 $298 \ K$ and $5 \ atm$ pressure is

The partial pressure of ethane over a solution containing $7.14 \times 10^{-3} \ g$ of ethane is $1 \ bar$. If the solution contains $5 \times 10^{-2} \ g$ of ethane,then what shall be the partial pressure of the gas (in $bar$)? (At equal temperature)

Explain the equilibrium in soda water and explain it using Henry's law.

At $T \ (K)$ the molarity of $CO_2$ (in $mol \ L^{-1}$) in $200 \ mL$ of soda water packed under a pressure of $3.4 \ bar$ is ($K_H$ of $CO_2$ in water is $1.7 \times 10^3 \ bar$ at $T \ (K)$).

What is solubility? What is a saturated solution?