Question

One example of change of colour

Answer 1

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TO SHOW THAT AIR CONTAINS CARBON DIOXIDE AND WATER CHANGES COLOUR.

Take a test tube fitted with a two-bored rubber-cork. Fit a long bent tube through one bore and fit a short bent tube through the other bore. Pour some fresh prepared lime water (calcium hydroxide solution) into the test tube.

Blow air by pump through the long tube. You will observe that air, bubbles through lime water and after some time the lime water turns milky (change in colour)

This shows that air contains carbon dioxide which made the change in colour.