Which of these is a strong acid?

**The reasoning** A **strong acid** is one that **completely ionizes** (breaks apart 100%) in water, releasing all its H⁺ ions. Hydrochloric acid (HCl) does exactly this: HCl → H⁺ + Cl⁻ (complete dissociation) When HCl dissolves, virtually every molecule splits, making it extremely acidic. This is why it's used in labs and even in your stomach for digestion! The others (acetic, carbonic, citric) are **weak acids** — they only partially ionize in water, so most molecules stay intact. For example, acetic acid (vinegar) releases maybe 1-5% of its H⁺ ions. **Why the wrong options tempt you** - **Acetic acid** (vinegar) tastes sour and seems strong, but it's actually weak - **Carbonic acid** (in soft drinks) fizzes aggressively, which feels "strong," but it barely ionizes - **Citric acid** (in oranges) has a sharp taste, fooling you into thinking it's strong The confusion: we mix up *corrosiveness* or *sourness* with *chemical strength*. They're different! **Quick takeaway** The common strong acids you MUST memorize: **HCl, H₂SO₄, HNO₃** — they ionize completely; everything else you meet in secondary school is likely weak.