Question

$\text{Zinc carbonate }\to \text{ Zinc oxide + carbon dioxide}$
Identify the type of reaction.

Answer 1

Hint: Try to understand the mechanism of the different types of reaction mentioned in the options. An example for each type of reaction will help you correlate to the equation mentioned above. The names of the reaction are almost self-explanatory.

Complete step-by-step answer:
- Neutralisation reaction can be defined as a chemical reaction such that an acid and a base react together quantitatively to form salt and water as products.
In neutralisation reaction, the hydrogen ions from acid and hydroxide ions from base form water and the remaining ions form the salt which is the product of neutralisation reaction. Example:
$\text{HA + BOH }\to \text{ BA + }{{\text{H}}_{2}}\text{O}$
Where BA is the salt formed.
- Decomposition reaction can be defined as a chemical reaction in which one reactant gives more than one product. An example is shown below:
$\text{AB }\to \text{ A + B}$
Where AB is considered as the parent or reactant molecule.
- A displacement reaction is defined as a reaction in which an atom or set of atoms is displaced by another atom/molecule. An example is shown below:
$\text{A + B-C }\to \text{ A-C + B}$
However, the above reaction is considered possible when the reactivity of A is more than B.
- A combination reaction also known as synthesis reaction is a reaction where two or more atoms or molecules combine to form a single compound as a product. An example is given below:
$\text{X +Y }\to \text{ XY}$
From the above explanations and examples, we can conclude that the reaction, $\text{Zinc carbonate }\to \text{ Zinc oxide + carbon dioxide}$ is a decomposition reaction.

Therefore, the correct answer is option (B).

Note: If you carefully read the explanations, you will notice that the mechanism for decomposition reaction is the exact opposite of combination reaction. This is because when we reverse a combination reaction (products become reactants and vice versa) it becomes a decomposition reaction.