Ca (s) + MgSO4 (AQ) - >CaSO4 (aq) + Mg

BaCl2 (aq) + K2So4 (aq) - >BaSo4 (s) + 2KCl

rewrite each reaction as a balanced net ionic equation.

First equation

1) Write the balanced equation

Ca (s) + MgSO4 (AQ) - >CaSO4 (aq) + Mg

2) Write the ionic equatin showing the oxidation states (charges), next to each ion

Ca (0) + Mg (2+) + SO4 (2-) - - - > Ca (2+) + SO4 (2-) + Mg (0)

3) Remove the spectator ions (those that appear exactly the same at both sides). In this case remove SO4 (2-) from both sides to get:

Net ionic equation

Ca (0) + Mg (2+) - - - > Ca (2+) + Mg (0)

Now go with the second equation

1) Write the balanced equation

BaCl2 (aq) + K2SO4 (aq) - >BaSO4 (s) + 2KCl

2) Write the ionic equation

Ba (2+) + 2Cl (1-) + 2K (1+) + SO4 (2-) - - - > Ba (2+) + SO4 (2-) + 2 K (1+) + 2Cl (1-)

3) Remove the spectator ions.

Here all the ions are spectator, because non of them changed the oxidation state. Then, there is not net ionic equation.