Question 1 Report
The diagram shows a bottle of scent opened at one side of a still room; people at the far side can soon smell it. Which statement explains how the scent molecules reach them?
The scent reaches the far side because its molecules are in constant random motion and, overall, move from where they are concentrated to where they are dilute, down the concentration gradient; this is diffusion. It does not need a draught, and osmosis refers only to water crossing a partially permeable membrane, not scent spreading through air. Diffusion always proceeds from high to low concentration, never the reverse.
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