Answer
(a) $[H^+] = 6.31 \times 10^{-6}M$
(b) $[H^+] = 1.00 \times 10^{-16}M$
(c) $[H^+] = 2.7 \times 10^{-6}M$
Work Step by Step
We will use the equations:
$[H^+] = 10^{-pH}$
$[H^+] * [OH^-] = 10^{-14}$
(a) $[H^+] = 10^{-5.20} = 6.31 \times 10^{-6}$
(b) $[H^+] = 10^{-16.00} = 1.00 \times 10^{-16} $
(c)
$[H^+] * 3.7 \times 10^{-9} = 10^{-14}$
$[H^+] = \frac{10^{-14}}{3.7 \times 10^{-9}} = 2.7 \times 10^{-6}$