Describe the trend in thermal stability of the nitrates and carbonates as each group is descended.?

Question

this is an experiment on heating the nitartes and carbonates of the s-block element.
Li2CO3, MgCO3, CaCO3, SrCO3, BaCO3, LiNO3, NaNO3, KNO3, Mg(NO3)2, Ca(NO3)2, Sr(NO3)2, Ba(NO3)2

what is the change on thermal stability when down the group?
Is increasing or decreasing down the group?

Answer 1

As you go down each group, the nitrates and carbonates decompose at higher temperatures ie they become more thermally stable. This is because the ionic character becomes greater as you go down the group.

Answer 2

they both give oxides on heating