To determine which reaction is a decomposition reaction, we need to understand the characteristics of different types of chemical reactions.
A decomposition reaction is a type of chemical reaction wherein a single compound breaks down into two or more simpler substances. The general form of a decomposition reaction can be represented as:
[tex]\[ AB \rightarrow A + B \][/tex]
Now, let's analyze each given reaction to see which one fits this description:
Option A: [tex]\( 2KClO_3 \rightarrow 2KCl + 3O_2 \)[/tex]
In this reaction, potassium chlorate (KClO3) breaks down into potassium chloride (KCl) and oxygen gas (O2). Here, a single compound is breaking down into two simpler substances. This matches the definition of a decomposition reaction.
Option B: [tex]\( 4Na + O_2 \rightarrow 2Na_2O \)[/tex]
This is a synthesis reaction where sodium (Na) and oxygen (O2) combine to form sodium oxide (Na2O). In a synthesis reaction, two or more simple substances combine to form a more complex compound.
Option C: [tex]\( ZnS + 3O_2 \rightarrow 2ZnO + 2SO_2 \)[/tex]
This is a combustion reaction where zinc sulfide (ZnS) reacts with oxygen (O2) to form zinc oxide (ZnO) and sulfur dioxide (SO2). Combustion reactions typically involve a substance reacting with oxygen to produce oxides.
Option D: [tex]\( 2NaBr + CaF_2 \rightarrow 2NaF + CaBr_2 \)[/tex]
This is a double-displacement reaction where sodium bromide (NaBr) and calcium fluoride (CaF2) exchange ions to form sodium fluoride (NaF) and calcium bromide (CaBr2).
Considering all the options, it is clear that the only reaction that fits the criteria for a decomposition reaction is:
Option A: [tex]\( 2KClO_3 \rightarrow 2KCl + 3O_2 \)[/tex]
Thus, the correct answer is Option A.
