Answer
$I$ is the correct letter.
Work Step by Step
1. Identify all solutions:
$C, F, G$ and $I$.
2. Analyze their hydronium concentrations:
$C$:
$[OH^-] * [H_3O^+] = Kw = 10^{-14}$
$ 3 \times 10^{- 5} * [H_3O^+] = 10^{-14}$
$[H_3O^+] = \frac{10^{-14}}{ 3 \times 10^{- 5}}$
$[H_3O^+] = 3.333 \times 10^{- 10}M$
So, this is not valid.
$F$:
Strong base: $[OH^-] = [LiOH] = 0.1M$
$[OH^-] * [H_3O^+] = Kw = 10^{-14}$
$ 0.1 * [H_3O^+] = 10^{-14}$
$[H_3O^+] = \frac{10^{-14}}{0.1}$
$[H_3O^+] = 1 \times 10^{- 13}M$
So, this is not valid.
$G:$
$[H_3O^+] = 2 \times 10^{-8}M$
So, this is not valid.
$I:$
Strong acid: $[H_3O^+] = [HClO_4] = 0.010M$
$[H_3O^+] = 0.010M$
This is valid: $0.010M > 1.0 \times 10^{-7}M$
