JEE Main levelSingle correct optionDifficulty 2 of 3sb185
Among BeCOX3, MgCOX3, CaCOX3 and BaCOX3, the carbonate with the lowest decomposition temperature is
ACaCOX3
BMgCOX3
CBeCOX3
DBaCOX3
Answer: C
Thermal stability of group 2 carbonates increases down the group. The very small, highly polarising BeX2+ distorts the carbonate ion most, so BeCOX3 decomposes at the lowest temperature.