Question

Which reaction is a decomposition reaction? A. 2KClO3 → 2KCl + 3O2 B. 4Na + O2 → 2Na2O C. ZnS + 3O2 → 2ZnO + 2SO2 D. 2NaBr + CaF2 → 2NaF + CaBr2

Answer 1

The answer is A for decomposition.

Answer 2

Answer : The decomposition reaction will be, (A)
`2KClO_3\rightarrow 2KCl+3O_2`

Explanation :

Decomposition reaction : It is defined as the reaction in which a single larger compound decomposes to produce two or more smaller molecules as a product.

The general representation of decomposition reaction is :

`AB\rightarrow A+B`

From the given options,

(A)
`2KClO_3\rightarrow 2KCl+3O_2` this reaction a decomposition reaction in which a potassium chlorate decomposes to give potassium chloride and oxygen gas as a product.

While the other reactions,

(B)
`4Na+O_2\rightarrow 2Na_2O` this reaction is a combination reaction in which the two or more molecules combine to form a larger single molecule as a product.

(C)
`ZnS+3O_2\rightarrow 2ZnO+2SO_2` this is a double displacement reaction in which the cation and the anion of the two reactant exchange their places to give two another compounds as a product.

(D)
`2NaBr+CaF_2\rightarrow 2NaF+CaBr_2` this is a double displacement reaction in which the cation and the anion of the two reactant exchange their places to give two another compounds as a product.

Hence, the decomposition reaction will be,
`2KClO_3\rightarrow 2KCl+3O_2`