The molarity of the solution obtained by dissolving 0.01 moles of $\mathrm{NaCl}$ in 500 ml of solution is 

We know that the formula of molarity can be mathematically expressed as: 

$\text{ Molarity }=\frac{\text{ Moles of solute }}{\mathrm{V}\text{ (litre) }}$

Substituting the quantities provided in the question:

$$\begin{gathered} =\frac{0·01}{500}\times 1000 \\ \Rightarrow 0·02 M \end{gathered}$$

Therefore, option C is the correct answer.