Answer:
Step-by-step explanation:
You don't normally do this, but you might start by balancing the complex ion which is NO3^-
There are 2 of these on the right side of the arrow so make two on the left.
CaO + 2HNO3 arrow Ca(NO3)2 + H2O
That looks balanced. Let's check it out.
Species Ca H NO3 O
Left 1 2 2 1 on the CaO
Right 1 2 2 1 on the H2O