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Which of the following are not decomposition reactions?

A) 2Mg + O₂ → 2MgO
B) CaO + H2O → Ca(OH)₂
C) NaOH → Na₂O + H₂O
D) KClO₃ → KCl + O₂

User Arany
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1 Answer

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Final answer:

The reactions 2Mg + O₂ → 2MgO (a synthesis or composition reaction) and CaO + H2O → Ca(OH)₂ (a combination reaction) are not decomposition reactions.

Step-by-step explanation:

The student is questioning which of the listed reactions are not decomposition reactions. A decomposition reaction is a type of chemical reaction in which one compound breaks down into two or more simpler substances. The reactions provided can be categorized based on this definition:

  • 2Mg + O₂ → 2MgO: This is not a decomposition reaction; it's a synthesis or composition reaction, as magnesium and oxygen combine to form magnesium oxide.
  • CaO + H2O → Ca(OH)₂: This is also not a decomposition reaction; it is a combination reaction, resulting in the formation of calcium hydroxide from calcium oxide and water.
  • NaOH → Na₂O + H₂O: This is a decomposition reaction, where sodium hydroxide decomposes into sodium oxide and water.
  • KClO₃ → KCl + O₂: This is another example of a decomposition reaction, where potassium chlorate breaks down into potassium chloride and oxygen gas.

According to these examples, 2Mg + O₂ → 2MgO and CaO + H2O → Ca(OH)₂ are not decomposition reactions, but rather are examples of composition or combination reactions.

User Phrogg
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