(a)[1]
When copper(II) carbonate is heated strongly, it breaks down in the same way as Group 2 carbonates. Predict what would be seen when anhydrous copper(II) carbonate is heated.
(b)[3]
Describe and explain how the thermal stability of the Group 2 carbonates changes down the group.
(c(i))[2]
Calcium cyanamide, $\text{CaCN}_2$, can be used as a fertiliser. Finish the ‘dot-and-cross’ diagram for the cyanamide ion, $\text{CN}_2^{2-}$. Use the following key for the electrons: electrons from carbon, electrons from nitrogen, added electron(s) that produce the overall negative charge.
(c(ii))[2]
$\text{CaCN}_2$ reacts quickly with water to give an insoluble white solid and ammonia only. Suggest an equation for this reaction.