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, $2KClO_3\rightarrow 2KCl+3O_2$