Question

Which of the following cannot decompose on heating to give CO2?

• A. Li2CO3
• B. Na2CO3
• C. KHCO3
• D. BaCO3

Answer 1

Answer: (B)

Na2CO3

Answer 2

Alkali metal carbonates except Li2CO3 are stable towards heat because they are most basic in nature and basic character increases down the group and thermal stability increases down the group.

Bigger HCO3– anion is polarised by smaller Li+ and thus readily decomposes to give CO2 gas.

Li2CO3 $\overset{\quad\Delta\quad}{\rightarrow}$Li2O + CO2