Verified answer

** I'm not a chemistry expert. I'm just looking at the subject again after many years. This is what I came up with after looking around.

Balanced equation :

NiCO3 (s) + 2 HNO3 (aq) ---> H2CO3 (aq) + Ni(NO3)2 (aq)

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ionic :

Ni(2+) + CO3(2-) + 2H(1+) + 2NO3(1-) ---> 2H(1+) + CO3(2-) + Ni(2+) + 2NO3(1-)

.. s .......... s .......... aq ......... aq .............. aq ........ aq ......... aq ......... aq

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net ionic :

NiCO3 (s) ---> Ni(2+) (aq) + CO3(2-) (aq)