Regarding molarity, which of the following statements are correct

a) Units of molarity $\mathrm{mol} {\mathrm{kg}}^{-1}$

b) Molarity of dibasic acid is half of its normality

c) Normality $\times$ GEW / GMW

d) Molarity always equals to its molality

We know that Molarity$=\frac{\mathrm{No}. \mathrm{of} \mathrm{moles} \mathrm{of} \mathrm{solute}}{\mathrm{Volume} \mathrm{of} \mathrm{solution}( \mathrm{in} \mathrm{litres})}$

Molarity $=\frac{\text{ Mass of solute }\times 1000}{\text{ Molar mass of solute× }\mathrm{V}\text{ (in }\mathrm{mL})}$

Therefore, Unit of molarity is $\mathrm{mol} {\mathrm{L}}^{-1}$ or $\mathrm{mol} {\mathrm{dm}}^{-3}$.

Hence, statement (a) is incorrect.

And, we also know that

Normality $=\mathrm{n}(\mathrm{net} \mathrm{valence})\times$ Molarity, 

for dibasic acid $\mathrm{n}=2$

Therefore, Molarity $=\frac{\text{ Normality }}{2}$

Molarity $=\frac{\text{ Normality }\times \text{ GEW }}{\text{ GMW }}=\frac{\text{ Mass per }{\mathrm{dm}}^3}{\text{ GMW }}$

Hence, statements (b) and (c) are correct.

And, statement (d) is also incorrect because it is not neccessary that molarity and molality are always equal.

Hence, option(b) is correct.