Which substance has a very low pH and burns on contact with immediate pain?

• A. Acids
• B. Alkalis
• C. Hydrocarbons
• D. Petroleum-based

Answer: (A)

pH indicates how acidic or basic a substance is, and substances with a very low pH are acids. Acids have a high hydrogen ion concentration, which quickly damages surface tissues and causes immediate burning and pain on contact. This sharp, quick pain is characteristic of acids because the rapid chemical reaction at the skin surface leads to rapid tissue disruption. Alkalis are bases with higher pH and tend to cause tissue injury through different chemical processes that can be deep and cause a more prolonged burn. Hydrocarbons and petroleum-based products aren’t defined by acidity or basicity, so their effects aren’t described by a very low pH and immediate burning in the same way. So, the description points to acids as the substance in question. If exposure occurs, flush with plenty of water.