The solubility of a gas in a liquid is directly proportional to the pressure of the gas over the solution. Identify the law for this statement.

The values of the Henry's law constant of $Ar$,$CO_{2}$,$CH_{4}$ and $O_{2}$ in water at $25^{\circ} C$ are $40.30$,$1.67$,$0.41$ and $34.86 \ kbar$,respectively. The order of their solubility in water at the same temperature and pressure is

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: Helium is used to dilute oxygen in diving apparatus.
Reason $R$: Helium has high solubility in $O_2$.
In the light of the above statements,choose the correct answer from the options given below:

Dry air contains $79 \% \,N_2$ and $21 \% \,O_2$. At $T \,K$, if Henry's law constants for $N_2$ and $O_2$ in water are $8.57 \times 10^4 \,atm$ and $4.56 \times 10^4 \,atm$ respectively, the ratio of mole fractions of $N_2$ and $O_2$ dissolved in water at $1 \,atm$ is

If the solubility of $NaCl$ at $20\,^{\circ}C$ is $35\,g$ per $100\,g$ of water,then on adding $50\,g$ of $NaCl$ to the same amount of water at the same temperature,the amount of salt that remains undissolved is .......... $g$.

Explain the factors affecting the solubility of salts in a solution.