Answer:
pH = 10
Explanation:
pH = -log [H⁺]
A solution that is pH = 4 has a [H⁺] = 1x10⁻⁴M
As the mixture of the two solutions is pH = 7 (Neutral). The second solution must contain the exact amount of OH⁻ to neutralize the H⁺ of the first solution. That is [OH⁻] 1x10⁻⁴
And as pOH = -log [OH⁻]
pOH = -log 1x10⁻⁴
pOH = 4
Also, pH = 14-pOH
pH of the second solution must be:
14 - 4
pH = 10
