IMO Practice Test — Matter & Mixtures
6 Questions • 12 min • Olympiad level
12:00
Question 1 of 6
hard
Why does a balloon shrink a little when put in a cold fridge?
Cold gas particles move closer together
The balloon eats air
Air turns solid
It loses colour
Explanation: Cooling makes gas particles draw closer, so the balloon shrinks.
Question 2 of 6
hard
Why is a fruit salad a good example of a mixture you can easily separate?
It cannot be undone
The fruits melt together
It becomes one new fruit
You can still pick out each fruit
Explanation: Each fruit keeps its identity and can be picked out.
Question 3 of 6
hard
A gas can dissolve in a liquid too; the fizz in soda water is dissolved…
Iron
Sand
Carbon dioxide gas
Oil
Explanation: Soda fizz is carbon dioxide gas dissolved in water.
Question 4 of 6
hard
Sea water is a mixture because it is water with dissolved…
Iron bars
Salts and minerals
Stones
Wood
Explanation: Sea water mixes water with dissolved salts.
Question 5 of 6
hard
To separate a mixture of two liquids like water and oil that do not mix, we can use a…
Filter paper only
Magnet
Fan
Separating funnel (let them settle)
Explanation: Oil and water settle in layers and can be drained apart.
Question 6 of 6
hard
Rainwater is fairly pure because, in the water cycle, it formed from water that had…
Evaporated, leaving impurities behind
Frozen solid
Been filtered by sand
Boiled in a pot
Explanation: Evaporation lifts pure water vapour, leaving salts behind.