On the pH scale, distilled water with $\mathrm{pH}=7$ at $25°C$ is considered:

On the pH scale, a change of 1 pH unit corresponds to a tenfold change in ${10}^{-\mathrm{pH}}$. How many times more acidic (in terms of ${H+}^{\mathrm{}}$ concentration) is a solution with pH 6 than a solution with pH 9?

Typical human stomach acid has a pH around 1–2. Approximately what is the hydronium ion concentration, $\left[H_3{O}^{+}\right]$, for a pH of 1.5?

On-the-scalp hair lighteners are formulated to be alkaline to open the hair cuticle and promote oxidation. Which pH range best describes most on-the-scalp lighteners?

Alkaline (basic) solutions have a pH in which of the following ranges at $25°C$?

Ammonium thioglycolate (often used in hair relaxers) is basic. Which pH range best matches ammonium thioglycolate relaxers?

On the pH scale, which pH range corresponds to acidic solutions?

In aqueous solution, the pH of a substance is a measure of its:

On the pH scale for aqueous solutions, what is the smallest possible pH value (theoretical, not limited by practical measurement)?