pH scale tells how acidic or basic a solution is, at 25 °C, if pH > 7 - basic ,
pH = 7 neutral and if pH < 7 then its an acidic solution.
pH can be calculated as follows;
pH = - log[H₃O⁺]
pH = - log (3.98 x 10⁻⁹ M)
pH = 8.400
therefore pH of the solution is 8.400
