(a)[2]
Describe what you would observe when calcium and barium are heated separately in oxygen. Give one observation for calcium and one for barium.
(b)[3]
The decomposition temperatures of the Group $2$ carbonates change down the group. State and explain the change in decomposition temperatures.
(c)[2]
Magnesium carbonate was heated in an open test-tube. It was hard to tell whether thermal decomposition had occurred. Explain why.