Answer
The complete table is:
Work Step by Step
First line:
$[H^+]:$
$pH < 7$
$-log[H^+] < 7$
$log[H^+] > -7$
$[H^+] > 10^{-7}$
If the $pH$ is less than 7, at 25$^{\circ}$ C, the solution is acidic.
Second line:
$pH:$
$[H^+] < 10^{-7}$
$log[H^+] < log(10^{-7})$
$log[H^+] < -7$
$-log[H^+] > 7$
$pH > 7$
If the pH is higher than 7, the solution is basic.
Third Line:
Neutral solution: $pH = 7$ and $[H^+] = 10^{-7}$:
Neutral: $[H^+] = [OH^-] = x$
$[H^+] * [OH^-] = 10^{-14}$
$x * x = 10^{-14}$
$x^2 = 10^{-14}$
$x = 10^{-7}$
$[H^+] = 10^{-7}$
Neutral: pH = pOH = y
$pH + pOH = 14$
$y + y = 14$
$2y = 14$
$y = 7$
$pH = 7$
