Which reaction is a decomposition reaction? a. 2kclo3 → 2kcl + 3o2 b. 4na + o2 → 2na2o c. zns + 3o2 → 2zno + 2so2 d. 2nabr + caf2 → 2naf + cabr2

Option A. 2KClO₃ → 2KCl + 3O₂

Explanation:

There are five basic general types of chemical reactions:

Decomposition reactionsSynthesis or combination reactionSingle replacement reactionsDouble replacement reactionsCombustion reactions

The given reactions are:

2KClO₃ → 2KCl + 3O₂

Which is, indeed, a decomposition reaction because the reactant, KClO₃, is a single substance that undergoes a reaction in which it yields two new substances, known as products: KCl and O₂.

4Na + O₂ → 2Na₂O is a synthesis or combination reaction because two reactants, Na and O₂, combine for the formation of one single new product, Na₂O.ZnS + 3 O₂ →  2ZnO + 2SO₂ is a single replacement reaction because oxygen is replacing Zn and S in ZnS to form ZnO and plus SO₂.2NaBr + CaF₂ → 2NaF + CaBr₂ is a double replacement reaction because two  ions (Br⁻ from NaBr and F⁻ from CaF₂) are exchanging places with other two ions (Na⁺ from NaBr and Ca²⁺ from CaF₂) two form two new ionic compounds (NaF and CaBr₂).