Complete and balance each of the following molecular equations, including phase labels, if a reaction occurs. Then

Question:

Complete and balance each of the following molecular equations, including phase labels, if a reaction occurs. Then write the net ionic equation. If no reaction occurs, write NR after the arrow.
a. HClO4 + BaCO3 →
b. H2CO3 + Sr(OH)2 →
c. K3PO4 + MgCl2 →
d. FeSO4 + MgCl2 →