Question

When calcium carbonate is heated, it decomposes to give ______________.
A) water
B) calcium oxide
C) carbon dioxide
D) None of these

Answer 1

Hint: During decomposition, the molecule breaks down into two or more than two simpler substances. The general representation of the decomposition reaction is given as follows: \[AB \to A + B\].

Complete step by step answer:
There are many forms of calcium carbonate present like limestone, marble, chalk, etc. Let us first discuss the two methods to prepare calcium carbonate.
Method 1: We can pass carbon dioxide through calcium hydroxide (slaked lime) to obtain calcium carbonate. The reaction is as follows.
\[Ca{\left( {OH} \right)_2} + C{O_2} \to CaC{O_3} + {H_2}O\]
Method 2: We can add sodium carbonate in calcium chloride to obtain calcium carbonate and sodium chloride. The reaction is as follows.
\[CaC{l_2} + N{a_2}C{O_3} \to CaC{O_3} + 2NaCl\]
We know that calcium carbonate is white fluffy power and is almost insoluble in water.
If we heat calcium carbonate to the temperature of 1200 K, it decomposes to form calcium oxide and evolve carbon dioxide gas. The reaction is as follows.
\[CaC{O_3}\xrightarrow{{1200K}}CaO + C{O_2} \uparrow \]
Here, the upper arrow on carbon dioxide indicates that the gas is evolved.

Therefore, we can conclude that the correct answers to this question are option B and option C.

Additional information:
Calcium carbonate is used as an important material for the manufacture of marbles and quick lime. High quality of papers is also manufactured with the help of precipitated calcium carbonate. As calcium carbonate is basic in nature, it is also used as an antacid. It is also used in toothpaste and is the constituent of chewing gum. Hence, we can say that calcium carbonate is highly used in the product used in daily activities.

Note:
Decomposition leads to two or simpler molecules. So, we have to choose the correct two options. As the molecular formula of calcium carbonate does not contain hydrogen, we can neglect water as the product.