Answer
See answer below.
Work Step by Step
a)$Ba(OH)_2(aq)+2\ HCl(aq)\rightarrow BaCl_2(aq)+2\ H_2O(l)$
Acid-base reaction
b) $2\ HNO_3(aq)+CoCO_3(s)\rightarrow Co(NO_3)_2(aq)+H_2O(l)+CO_2(g)$
Gas-forming reaction
c)$2\ Na_3PO_4(aq) +3\ Cu(NO_3)_2(aq) \rightarrow Cu_3(PO_4)_2(s)+6\ NaNO_3(aq)$
Precipitation reaction