IMO Practice Test — Materials Around Us
6 Questions • 15 min • Olympiad level
15:00
Question 1 of 6
A spoonful of sugar is stirred into water until it disappears. The sugar has:
Vanished forever
Dissolved and is still present in the water
Turned into water
Become insoluble
Explanation: Dissolved sugar is still there (the water tastes sweet); it has not vanished.
Question 2 of 6
Two materials are tested: X lets you read print through it clearly, Y blurs the print but still lets light through. Then:
X is transparent, Y is translucent
X is opaque, Y is transparent
Both are opaque
X is translucent, Y is transparent
Explanation: Clear viewing = transparent (X); blurred but lit = translucent (Y).
Question 3 of 6
A material is shiny, hard and opaque, and sinks in water. It is most likely a:
Piece of cotton
Metal
Sheet of glass
Dry leaf
Explanation: Shiny, hard, opaque and dense (sinks) describes a metal.
Question 4 of 6
Why can the SAME material appear in more than one group when we classify?
Because materials keep changing
Because the group depends on which property we choose
Because classification is wrong
Because all materials are the same
Explanation: Different properties put a material into different groups (e.g. glass is hard and transparent).
Question 5 of 6
You must lift only the iron objects out of a mixture of iron nails, sugar and sand. The quickest way is to:
Add water
Use a magnet
Heat the mixture
Shine light on it
Explanation: A magnet attracts the iron nails, separating them quickly (using a property of the material).
Question 6 of 6
A ball of clay sinks, but the same clay shaped like a bowl floats. This shows that floating depends on:
Only the colour
The shape as well as the material
Only the weight
Nothing at all
Explanation: The same material can float or sink depending on its shape.