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Online Class 9 Science Notes - Chapter 2 – Is Matter Around us Pure

Online Class 9 Science Notes - Chapter 2 – Is Matter Around us Pure

Compounds

A compound is a substance made up of two or more elements chemically combined in the fixed proportion by mass.
Eg:-Water is a compound made up of two elements hydrogen and oxygen, chemically combined in a fixed proportion of 1:8 by mass.
Some of the examples of compounds are – Ammonia, carbon dioxide, ice, steam, methane, glucose, baking soda and sodium hydroxide.
Compounds can be further divided into three classes:-
  • Acids
  • Base
  • Salts
For questions answers, worksheets on Food, click Class 9th Science.
Properties of Compound
  • A compound cannot be separated into its components by physical methods.
  • The properties of a compound are entirely different from those of its constituent elements
  • Energy is usually either given out or absorbed during the preparation of a compound.
  • A compound has a fixed melting and boiling point
  • The composition of a compound is fixed; the constituents are present in a fixed proportion by mass.
  • A compound is a homogeneous mixture. It appears to be same throughout its mass.

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