Question 15

The chemical equation Cr + Fe(NO₃)₂ → Fe + Cr(NO₃)₂ is an example of a single replacement reaction.

This reaction involves chromium (Cr) replacing iron (Fe) in iron(II) nitrate (Fe(NO₃)₂), resulting in the formation of iron and chromium(II) nitrate (Cr(NO₃)₂), which characterizes it as a single replacement reaction.

A) Single replacement

This option is correct because a single replacement reaction occurs when one element replaces another in a compound. In this case, chromium displaces iron from iron(II) nitrate, demonstrating the fundamental nature of this reaction type.

B) Decomposition

Decomposition reactions involve a single compound breaking down into two or more simpler substances. This reaction does not fit that description, as it involves the exchange of elements rather than the breakdown of a single compound.

C) Double replacement

Double replacement reactions occur when two compounds exchange partners to form two new compounds. This reaction does not involve the exchange of ions between two compounds but rather a single element displacing another, making this option incorrect.

D) Combustion

Combustion reactions typically involve a substance reacting with oxygen to produce heat and light, often resulting in the formation of carbon dioxide and water. This reaction does not involve combustion, thereby ruling out this option.

Conclusion

The reaction Cr + Fe(NO₃)₂ → Fe + Cr(NO₃)₂ exemplifies a single replacement reaction, where chromium replaces iron in a compound. All other options misrepresent the nature of the reaction, as they pertain to different types of chemical processes that do not apply in this context.