The density of a $3 \, M \, NaCl$ solution is $1.25 \, g \, mL^{-1}$. Calculate the molality of the solution. (in $, m$)

$A$ solution is prepared by adding $2 \ g$ of a substance $A$ to $18 \ g$ of water. Calculate the mass per cent of the solute. (in $\%$)

The molarity of a solution obtained by mixing $750 \, mL$ of $0.5 \, M \, HCl$ with $250 \, mL$ of $2 \, M \, HCl$ will be $......... \, M$.

The number of moles of $NaOH$ in $2 \ L$ of $0.5 \ M \ NaOH$ solution is ..........

An antifreeze solution is prepared from $222.6 \ g$ of ethylene glycol $(C_2H_6O_2)$ and $200 \ g$ of water. Calculate the molality of the solution. If the density of the solution is $1.072 \ g \ mL^{-1}$,then what shall be the molarity of the solution?

If the density of some lake water is $1.25\, g\, mL^{-1}$ and contains $92\, g$ of $Na^{+}$ ions per $kg$ of water,calculate the molality of $Na^{+}$ ions in the lake. (in $, m$)