# "Explain" questions — Cambridge International IGCSE Chemistry (0620)

> 100 questions · chemistry

## How to answer

WHAT + WHY. Every point paired with a because. Structure: X happens because Y. This causes Z because … Assessment Objective: AO2. Every "explain" answer on this spec is marked against exactly this pattern.

## Sample questions

1. [Explain the difference between an exothermic reaction and an endothermic reaction, and give one example of each type of …](https://www.gradenine.co.uk/q/explain-the-difference-between-an-exothermic-006a1b6d)
2. [Propanoic acid is a carboxylic acid used as a food preservative. Explain why propanoic acid is described as a weak acid,…](https://www.gradenine.co.uk/q/propanoic-acid-is-a-carboxylic-acid-05a51276)
3. [Hydrogen peroxide decomposes into water and oxygen when manganese(IV) oxide is added as a catalyst. A student measures t…](https://www.gradenine.co.uk/q/hydrogen-peroxide-decomposes-into-water-and-0725eba3)
4. [A farmer wants to use ammonium sulfate as a fertiliser on a field of wheat. State what type of compound ammonium sulfate…](https://www.gradenine.co.uk/q/a-farmer-wants-to-use-ammonium-14405496)
5. [Zinc powder is added to copper(II) sulfate solution. The blue colour of the solution fades and a reddish-brown solid for…](https://www.gradenine.co.uk/q/zinc-powder-is-added-to-copper-ii-1564d3df)
6. [Explain how the number of protons, neutrons and electrons in an atom determines its atomic number, mass number and overa…](https://www.gradenine.co.uk/q/explain-how-the-number-of-protons-15acae99)
7. [Explain why increasing the temperature of a reaction mixture increases the rate of a chemical reaction.](https://www.gradenine.co.uk/q/explain-why-increasing-the-temperature-of-17e1c4d3)
8. [A small amount of perfume is sprayed at one end of a long room. After a few minutes, the scent can be detected at the ot…](https://www.gradenine.co.uk/q/a-small-amount-of-perfume-is-19e3d6dc)

## Related

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