Which of the carbonates given below is unstable in air and is kept in `CO_(2)` atmosphere to avoid decomposition?

Options

A. `BeCO_(3)`
B. `MgCO_(3)`
C. `CaCO_(3)`
D. `BaCO_(3)`

Answer

A

Explanation

`BeCO_(3)` is unstable to the extent that it is stable only in atmosphere of `CO_(2).BeCO_(3)` shows reversible reaction because stability of oxide formed is more than carbonates.
`BeCO_(3)hArr BeO +CO_(2)`
`BeCO_(3)` is unstable due to strong polarising effect of small `Be^(2+)` ion on the large polarisable carbonation. Moreover, an extrastability of the oxide achieved through lattice energy by packing small cation with small oxide ion.