A student investigating diffusion places a drop of potassium permanganate crystal at the bottom of a beaker of still water. The purple colour gradually spreads throughout the water. Which statement best explains this observation?

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Question

A student investigating diffusion places a drop of potassium permanganate crystal at the bottom of a beaker of still water. The purple colour gradually spreads throughout the water. Which statement best explains this observation?

Accepted Answer

The purple particles and water particles are in constant random motion — Award 1 mark for identifying that both types of particles are in constant random motion, causing diffusion. A is incorrect — water particles do not systematically push in one direction. B is incorrect — the particles dissolve but do not evaporate within the liquid. D is incorrect — the question specifies still water, and diffusion occurs even without convection.

Answer

The purple particles and water particles are in constant random motion

Answer

Convection currents carry the purple colour upward

Answer

Water particles push the purple particles upwards

Answer

The purple particles dissolve and then evaporate

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One real Chemistry question.
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