An aqueous solution of $98\% (w/w)$ $H_2SO_4$ has a density of $1.84 \ g/mL$. The molality of the solution is: (in $m$)

Calculate the mole fraction of solute in the solution if the solution is prepared by dissolving $394 \ g$ of a nonvolatile solute in $622 \ g$ of water at $30^{\circ}C$ (Molar mass of solute $= 342 \ g \ mol^{-1}$).

$x$ grams of water is mixed in $69 \ g$ of ethanol. The mole fraction of ethanol in the resultant solution is $0.6$. What is the value of $x$ in grams?

Two solutions of a substance are mixed as follows: $480 \ mL$ of $1.5 \ M$ first solution + $520 \ mL$ of $1.2 \ M$ second solution. The molarity of the final solution will be ............. $M$.

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: At $10^{\circ} C$,the density of a $5 \ M$ solution of $KCl$ is given. The solution is cooled to $-21^{\circ} C$. The molality of the solution will remain unchanged.
Reason $R$: The molality of a solution does not change with temperature as mass remains unaffected by temperature.
In the light of the above statements,choose the correct answer from the options given below:

State the various methods of expressing the concentration of a solution.