Answer:
The answer to your question is: [H+] = 10⁻¹²
Explanation:
Remember that pH = -log [H+], then, in this exercise we need to calculate the pH of the substances and compare the results, the one which the higher value will be the strongest base.
a) [H+] = 10^-9 pH = -log[10⁻⁹] = 8
b) [H+] = 10^-11 pH = -log[10⁻¹¹] = 10
c) [H+] = 10^-10 pH = -log[10⁻¹⁰] = 9
d) [H+] = 10^-12 pH = -log[10⁻¹²] = 11 This is the strongest base