Which of the following methods of expressing concentration does not change with temperature?

The molality of $648 \ g$ of pure water is ........... $m$.

How are $0.50 \, mol$ $Na_{2}CO_{3}$ and $0.50 \, M$ $Na_{2}CO_{3}$ different?

The formula weight of $H_2SO_4$ is $98$. The weight of the acid in $400 \ mL$ of $0.1 \ M$ solution is ........... $g$.

$x \ g$ of $NaCl$ is added to water in a beaker with a lid. The temperature of the system is raised from $1^{\circ}C$ to $25^{\circ}C$. Which out of the following plots is best suited for the change in the molarity $(M)$ of the solution with respect to temperature? [Consider the solubility of $NaCl$ remains unchanged over the temperature range]

What would be the molality of $20\%$ (mass/mass) aqueous solution of $KI$? (Molar mass of $KI = 166 \, g \, mol^{-1}$)