For a neutral, aqueous solution, which of the following are always true?
1) Regardless of temperature, pKw = 14.
2) Regardless of temperature, [H⁺] = [OH⁻].
3) Regardless of temperature, pKa + pKb = pKw.
4) Regardless of temperature, pOH = 7.
5) Regardless of temperature, pH = 7.