Question

question 1 of 10
which of the following is an example of a decomposition reaction?

a. $\ce{zn + 2hcl -> zncl_{2} + h_{2}}$

b. $\ce{h_{2} + cl_{2} -> 2hcl}$

c. $\ce{2nacl -> 2na + cl_{2}}$

d. $\ce{cacl_{2} + na_{2}co_{3} -> caco_{3} + 2nacl}$

Explanation:

A decomposition reaction is a type of chemical reaction where a single compound breaks down into two or more simpler substances. Let's analyze each option:

• Option A: \( \text{Zn} + 2\text{HCl}

ightarrow \text{ZnCl}_2 + \text{H}_2 \) is a single - displacement reaction (a metal displaces hydrogen from an acid).

• Option B: \( \text{H}_2+\text{Cl}_2

ightarrow 2\text{HCl} \) is a combination (synthesis) reaction, where two substances combine to form a single compound.

• Option C: \( 2\text{NaCl}

ightarrow 2\text{Na}+\text{Cl}_2 \) shows a single compound (sodium chloride) breaking down into two simpler substances (sodium and chlorine gas), which fits the definition of a decomposition reaction.

• Option D: \( \text{CaCl}_2+\text{Na}_2\text{CO}_3

ightarrow \text{CaCO}_3 + 2\text{NaCl} \) is a double - displacement reaction (ions are exchanged between two compounds).

Answer:

C. \( 2\text{NaCl}
ightarrow 2\text{Na} + \text{Cl}_2 \)