Question

The carbonate that is least stable thermally is:

• A. $BeC{O}_3$
• B. $MgC{O}_3$
• C. $BaC{O}_3$
• D. $CaC{O}_3$

Answer 1

The correct option is A $BeC{O}_3$

As we move down the group, the size of the cations increases. Thus, the thermal stability also increases down the group. Since the size of $Be$ is the smallest and it has a high charge density , $BeC{O}_3$ is the least stable thermally.