When a metal carbonate is heated at 100°C, which of the following compounds will readily decompose?

Explanation

The thermal stability of metal carbonates increases down a group in the periodic table because the larger cations (lower down the group) have a lower charge density. This reduces their polarizing effect on the carbonate ion, making the carbonate more stable and less likely to decompose.Key Points:BeCO₃ (Beryllium Carbonate):Beryllium is the smallest and most polarizing cation in Group 2.It strongly distorts the carbonate ion, making it unstable and prone to decomposition even at relatively low temperatures.MgCO₃ (Magnesium Carbonate):Magnesium has a slightly larger ionic radius than beryllium, making MgCO₃ more stable than BeCO₃ but less stable than heavier carbonates.BaCO₃ (Barium Carbonate) and SrCO₃ (Strontium Carbonate):Barium and strontium are larger cations, making their carbonates the most stable in the group. They decompose only at very high temperatures.Thermal Stability Trend:BeCO₃<MgCO₃<SrCO₃<BaCO₃Conclusion:BeCO₃ readily decomposes when heated at 100°C due to its low thermal stability