$A$ solution is obtained by mixing $300 \, g$ of $25 \%$ solution and $400 \, g$ of $40 \%$ solution by mass. Calculate the mass percentage of the resulting solution. (in $\%$)

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:

How many grams of $CH_3OH$ should be added to water to prepare $150 \ mL$ solution of $2 \ M \ CH_3OH$?

The molality of the solution prepared by dissolving $125 \ mL$ of pure methanol $(d = 0.8 \ g \ mL^{-1})$ in $375 \ g$ of ethanol is

Calculate the mass fraction and mass percentage of aspirin in a solution prepared by dissolving $3.65 \, g$ of aspirin in $25.08 \, g$ of water.

The mole fraction of a solute in a solution is $0.1$. At $298 \ K$,molarity of the solution is the same as its molality. The density of this solution at $298 \ K$ is $2.0 \ g \ cm^{-3}$. The ratio of the molecular weights of the solute and solvent,$\left(\frac{MW_{solute}}{MW_{solvent}}\right)$,is