Answer
Please see the work below.
Work Step by Step
We know that the molecular equation is
$Hg(NO_3)_2+H_2S\rightarrow HgS+2HNO_3$
and net ionic equation is
$Hg^{+2}+H_2S\rightarrow HgS+2H^+$
The acid formed is nitric acid a strong acid and the product is mercury sulfide.