Question

how are chemical changes classified based on their special features
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Answer 1

Chemical changes are the result of chemical reactions. Chemical reactions are classified in :
1) Combination reaction :
C+O₂→ CO₂

2) Decomposition reaction :

CaCO₃ → CaO+CO₂

3) Displacement reaction or single displacement reaction :
Zn+2HCl → ZnCl₂+H₂

4) Double displacement reaction :
NaCl+AgNO₃ → AgCl+NaNO₃

5) Redox reaction : Acid base reaction :
HCl+NaOH → NaCl+H₂O

6) Redox reaction :

2S₂O₃ ^2-+I₂ → S₄O₆ ^2-+2I