Common salt formula.

**The reasoning** Common salt is the everyday substance we sprinkle on our jollof rice and use to cook soup. Its chemical name is **sodium chloride**, which tells us it contains sodium (Na) and chlorine (Cl). When these two elements combine, sodium donates one electron to chlorine, forming an **ionic bond**. Since sodium has a +1 charge and chlorine has a -1 charge, they combine in a 1:1 ratio, giving us **NaCl**. **Why the wrong options tempt you** - **KCl** (potassium chloride) looks similar because potassium is also in Group 1 like sodium, but it's used as a salt substitute, not our everyday table salt. - **CaCl₂** (calcium chloride) might confuse you because calcium is common (in bones, chalk), but notice the subscript 2 — calcium needs two chlorine atoms. - **MgCl₂** (magnesium chloride) has the same subscript issue; magnesium also needs two chlorines to balance its +2 charge. **Quick takeaway** Common salt = NaCl because **"Na" sounds like "nah" as in "nah, I need salt!"** — and it's the only option with a simple 1:1 ratio of metal to chlorine.