Which alkaline earth metal carbonate decomposes most easily?

Step-by-step solution

The thermal stability of alkaline earth metal carbonates increases down the group from Be to Ba . This is because as the size of the cation increases, its polarizing power decreases. A smaller cation like Mg²⁺ polarizes the large carbonate ion ( CO₃²⁻ ) more effectively, weakening the C-O bond and facilitating its decomposition into the metal oxide and CO₂ . The order of thermal stability is MgCO₃ Therefore, MgCO₃ has the lowest thermal stability among the given options and decomposes most easily. Answer: MgCO ₃