pH categories for acids and caustics?

• A. Acids < 7; Caustics > 7.
• B. Acids > 7; Caustics < 7.
• C. Acids = Caustics = 7.
• D. pH does not relate to acids or caustics.

Answer: (A)

pH shows how acidic or basic a solution is. Acids increase hydrogen ion concentration, which lowers the pH below 7. Caustics are bases, so they raise hydroxide levels and push the pH above 7. So acids have a pH less than 7, while caustics have a pH greater than 7 (neutral is 7). The other options mix up that relationship or ignore how pH reflects acidity and basicity.