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Is Matter Around Us Pure? — Science STD 9 — Question

Gujarat BoardEnglish MediumSTD 9ScienceIs Matter Around Us Pure?3 Marks
Question
State three reasons why you think air is a mixture and water is a compound.
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Answer

Air is a mixture because:
  1. Air can be separated into its constituents like oxygen, nitrogen, etc. by physical process of fractional distillation.
  2. Air shows the properties of all the gases present in it.
  3. Liquid air does not have a fixed boiling point.
Water is compound because:
  1. Water cannot be separated into its constituents, hydrogen and oxygen by physical methods.
  2. Heat and light are given out when water is prepared by burning hydrogen in oxygen.
  3. Water has standard b.p. of 100°C under standard atmospheric pressure.

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