Core5 mapped NDA questions
Build the idea
Build exam-ready understanding by connecting the core idea, formulas or facts, worked example and previous NDA questions. Focus on why each rule works, then test it under timed conditions.
Concept
An element is made of one kind of atom; a compound is two or more elements chemically combined in a fixed ratio; a mixture is a physical combination in any ratio that keeps the components' properties.
Compounds have fixed properties; mixtures do not.
Key Points & Formulas
- Element: e.g., oxygen, gold, hydrogen.
- Compound: e.g., water (H₂O), common salt (NaCl) — fixed ratio, new properties.
- Mixture: e.g., air, soil, brass — variable ratio, separable physically.
- Mixtures are separated by filtration, distillation, evaporation, etc.
Worked Example
Q. Classify water, air and oxygen as element/compound/mixture.
Oxygen — element (single kind of atom).
Water — compound (H and O combined in a fixed ratio).
Air — mixture (several gases, variable proportions).