Answer
pH is defined as the negative of the log (base 10) of the hydronium ion concentration:
$$pH = -log[H_3O^+] = -log[H^+]$$
Acidic solution: $pH \lt 7$
Neutral solution: $pH = 7$
Basic solution: $pH \gt 7$
Work Step by Step
pH is defined as the negative of the log (base 10) of the hydronium ion concentration:
$$pH = -log[H_3O^+] = -log[H^+]$$
Acidic solution: $pH \lt 7$
Neutral solution: $pH = 7$
Basic solution: $pH \gt 7$