Molarity can be expressed as moles per liter of solution We can simply write it as:

Molarity = moles/ Volume of solution (in liters)

In the problem we are looking for the amount of moles in the solution.We can solve that if we transform the equation as:

moles = Molarity x Volume of solution(L)

Given:

Molarity = 13 (M or moles/L)

Volume = 5.3mL

**notice that The volume is in mL so we have to convert mL to L first before proceeding to the next step.

1L = 1000mL

5.3 mL x 1L/1000mL   = 0.0053L

Now we can solve the number of moles:

moles nitric acid  = 13moles/L x 0.0053 L

                          = 0.0689 moles nitric acid

                          = 0.069 or 6.9x10^-2 moles nitric acid