Science (086) — AI-generated practice question

A skeletal chemical equation is an unbalanced chemical equation where the reactants and products are represented by their chemical formulae but the number of atoms of each element is not equal on both sides. For example: Mg + O₂ → MgO is a skeletal equation.

The Law of Conservation of Mass makes it necessary to balance such an equation. It states that mass can neither be created nor destroyed in a chemical reaction, so the number of atoms of each element must be the same on both sides.

Source: Chapter 1, Sections 1.1.1 and 1.1.2

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• 1 mark for defining skeletal equation (unbalanced, formulae written but atoms unequal on both sides).
• 1 mark for naming and stating the Law of Conservation of Mass.
• Examiners expect the law to be named, not just described. A brief example (like Mg + O₂ → MgO) strengthens the definition but is not compulsory.