Chemistry - Concentration Terms Question with Solution | TestHub

$1.25$ molal NaOH solution means, $1.25$ moles of $\mathrm{NaOH}$ are present in $1000\mathrm{g}$ of water $\therefore$ Weight of $\mathrm{NaOH}=1.25\times 40=50\mathrm{g}$ Weight of solution $=1000+50=1050\mathrm{g}$ $\%$ (by weight) of $\mathrm{NaOH}$ $$\begin{array}{l}=\frac{\text{ wt. of solute }}{\text{ wt. of solution }}\times 100\\ =\frac{50}{1050}\times 100=4.76\%\end{array}$$