Is a solution whose [H+] = 4.0 x 10^-12 M acidic, basic, or neutral

Is a solution whose [H+] = 4.0 x 10^-12 M acidic, basic, or neutral?

How can I go about determining this, since I'm not given the pH?

The answer is determined through the equation:

pH=-log([H+])

Then it is just plug and chug.

pH=-log(4.0*10^-12)

pH=11.4

Therefore, the solution is basic at standard state conditions.

if one were to look at the number for the concentration of H+, the exponent is < -7. if the exponent of the concentration is < -7, the solution is basic. if the exponent is > -7, the solution is acidic.
if it is -7, you will have to determine the -log of the [H+] to calculate the pH.

if we were to calculate the pH of this concentration, we would take the -log of the [H+]
-log(4x10^-12) = 11.4 = pH

basic. Because the concentration o2 [OH-]=2.5x10^-3 which is far larger than [H+].
remember that always [H]x[OH]=10^-14