What does a chemical equation convey?

• A. It uses only letters.
• B. It uses only numbers.
• C. It uses symbols and formulas to represent substances.
• D. It uses images instead of text.

Answer: (C)

Chemical equations communicate what happens in a reaction by using symbols and formulas to name the substances involved and to show how much of each one participates. Substances are written with their chemical formulas (for example H2, O2, NaCl), not just plain words or pictures. The equation uses plus signs to separate reactants, an arrow to show the transformation to products, and coefficients in front of formulas to indicate the relative amounts of each substance. This concise, standardized format lets us check which substances react and what is produced, and it also helps ensure mass is balanced on both sides. The other ideas—using only letters, only numbers, or images—don’t clearly identify the substances or show the change in a universally accepted way.