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
Oxygen and hydrogen are key non-metals with distinctive preparations and tests. Oxidation is the gain of oxygen / loss of electrons; reduction is the reverse. Together they form redox reactions.
Use the memory aid OIL RIG: Oxidation Is Loss, Reduction Is Gain (of electrons).
Key Points & Formulas
- Oxygen supports combustion; relights a glowing splint.
- Hydrogen burns with a 'pop' sound; it is the lightest gas.
- Oxidation: gain of oxygen / loss of hydrogen or electrons.
- Reduction: loss of oxygen / gain of hydrogen or electrons.
Worked Example
Q. In the reaction 2Mg + O₂ → 2MgO, what is oxidised?
Magnesium gains oxygen to form MgO.
Gain of oxygen = oxidation.
So magnesium is oxidised (and oxygen is reduced).