Rank the following solvents in decreasing order of their ability to dissolve the given solute (naphthalene).

Solubility curves of four ionic salts $X$,$Y$,$Z$,and $W$ are given below. In which case is the value of $\Delta H_{sol.} < 0$?

At $298 \ K$,how many millimoles of $CO_2$ gas will dissolve in $900 \ mL$ of water when $CO_2$ gas is passed through it? The $K_H$ value is $6.02 \times 10^{-4} \ bar$ and the partial pressure of $CO_2$ gas is $2 \times 10^{-8} \ bar$.

Calculate $K_H$ when $2 \ mmol$ of $O_2$ dissolve in $540 \ mL$ of water at $27 \ ^oC$ temperature. Given $P_{O_2} = 2 \times 10^{-8} \ bar$.

Why is a mixture of $He-O_2$ used by deep-sea divers instead of a $N_2-O_2$ mixture?

Assertion: $A$ mixture of $He$ and $O_2$ is used for respiration for deep sea divers.
Reason: $He$ is soluble in blood.