Question

The molality of dilute aqueous solution of $0.05M$ $NaOH$ is:

• A. $0.05m$
• B. $18.5m$
• C. $55.55m$
• D. $0.1m$

Answer 1

Answer: (A)

$0.05m$

Let the volume of solution be $1$ litre

$\therefore$ Molarity$=\frac{MolesofNaOH}{Volumeofsolution\left(inL\right)}$

$\therefore 0.05=$Moles of $NaOH$

Now, Mass of solvent=$Volume\times Density$

$=1\times 1$

$=1kg$

$\therefore$ Molarity$=\frac{MolesofNaOH}{Massofsolvent(i.e.H_{2}O)inkg}$

$=\frac{0.05}{1}$

$=0.05m$