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Physical and Chemical Changes — CHEMISTRY STD 7 — Question

ICSE BoardEnglish MediumSTD 7CHEMISTRYPhysical and Chemical Changes4 Marks
Question
Write the characteristics of chemical changes.
✓

Answer

Characteristics of a chemical change :
  1. One or more new substances are formed with composition and properties different from the original substances.
  2. The change is permanent and irreversible.
  3. An energy change is generally involved in a chemical change. Energy is either absorbed or evolved during a chemical change. Absorption of heat energy in a chemical reaction is called endothermic while evolution of heat energy is called exothermic reaction.
  4. The mass of the substances undergoing a chemical change is generally altered. However, the total mass of the substances involved in a chemical change remains the same. Mass is neither created nor destroyed during a chemical change.

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