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Chemical Changes and Reactions — CHEMISTRY STD 9 — Question

ICSE BoardEnglish MediumSTD 9CHEMISTRYChemical Changes and Reactions2 Marks
Question
State the conditions necessary for a chemical change or reaction.
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Answer

  1. close contact: for a chemical reaction to take place the reactants must come into close contact i.e., they should be mixed
  2. light: some reactions take place in the presence of light example- photosynthesis Carbon dioxide + water chlorophyll kn presence of sunlight glucose + oxygen
  3. Solution form: some substances react with each other when they r mixed in the solution form .
  4. catalyst: some reactions need a catalyst for speed up and down the reaction of e.g.manganese dioxide.

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