What kind of attractions are present in an aqueous solution of $NaCl$?

$K_{H}$ values for $H_2, CO_2, CH_4$ and $O_2$ at $298 \ K$ are $71.18, 1.67, 41.85$ and $34.86 \ kbar$ respectively. Arrange these gases in the increasing order of their solubility.

If $CO_2$ gas having a partial pressure of $1.67 \ bar$ is bubbled through $1 \ L$ water at $298 \ K$,the amount of $CO_2$ dissolved in water in $g \ L^{-1}$ is approximately. (Henry's law constant of $CO_2$ is $1.67 \ kbar$ at $298 \ K$)

Observe the following data given in the table $(K_H = \text{Henry's law constant})$. The correct order of solubility of these gases is:

Gas	$K_H$ (kbar at $298 \ K$)
$CO_2$	$1.67$
$Ar$	$40.3$
$HCHO$	$1.83 \times 10^{-5}$
$CH_4$	$0.413$

In which solution,the solubility of the solute decreases with an increase in temperature?

How many millimoles of nitrogen dissolve when nitrogen is passed in $1 \ L$ water at $293 \ K$ temperature? $[$ The value of $K_H$ is $7.648 \times 10^4 \ bar$ and partial pressure of $N_2$ gas is $0.987 \ bar.]$