Question

When $N{{a}_{2}}C{{O}_{3}}\left( s \right)$ is heated, it gives-
[A] $N{{a}_{2}}O$
[B] $C{{O}_{2}}$
[C] Both [A] and [B]
[D] $N{{O}_{2}}$

Answer 1

Hint: To answer this you should know that $N{{a}_{2}}C{{O}_{3}}\left( s \right)$ is a carbonate of sodium. When we heat it, it gives the corresponding oxide and emits a harmful gas. You can use this to answer the given question.

Complete step by step solution:
We know that $N{{a}_{2}}C{{O}_{3}}\left( s \right)$ is sodium carbonate. Sodium carbonate undergoes decomposes when heated. This type of decomposition is known as thermal decomposition. Before answering this question, let us discuss what a decomposition reaction is. We know that chemical reactions are of different types and we can classify them according to their working mechanism like combination or decomposition etc.
-Decomposition reaction- It is the type of chemical reaction in which a single compound breaks down into two or more elements. These reactions can be represented as-
\[AB\to A+B\]
In decomposition reaction, as we can see from the above reaction that a bond is broken to give us two (or more) products form a single compound. These reactions are generally endothermic, as breaking of bond requires a high amount of energy. A simple example of decomposition reaction is hydrolysis of water where a water molecule is broken down into hydrogen and oxygen gas.
 We can write the reaction as-
\[2{{H}_{2}}O(l)\to 2H(g)+{{O}_{2}}(g)\]
There are some compounds (like metal carbonates) that readily decompose when exposed to high heat while others do not-
\[MC{{O}_{3}}\xrightarrow{\Delta }MO+C{{O}_{2}}\]
The metal is denoted as ‘M’ in the above reaction where metal carbonates when heated decomposes into its oxide and releases carbon dioxide. In the given question also we have a metal carbonate. It decomposes into metal oxide and gives us carbon dioxide gas. We can write the reaction as-
\[N{{a}_{2}}C{{O}_{3}}\xrightarrow{\Delta }N{{a}_{2}}O+C{{O}_{2}}\]
The reaction above takes place at about 500 degree Celsius. We can see that the products are both $N{{a}_{2}}O$ and $C{{O}_{2}}$.

Therefore, the correct answer is option [C] Both [A] and [B]

Note: Decomposition reactions are generally disproportionation reactions. Here, the same compound oxidises and reduces to give us two different products. But, not all decomposition reactions are disproportionation reactions. For example, decomposition of carbonic acid does not involve reduction or oxidation.
\[{{H}_{2}}C{{O}_{3}}\to {{H}_{2}}O+C{{O}_{2}}\]