Answer:
The correct answer is two nitrogen atoms.
Step-by-step explanation:
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In the molecule of Ni (NO3) 2 there are two nitrogen atoms. This is a reaction between a compound with Nickel (Ni) that has a valence number +2, and the nitrogen acid. When the hydrogen atom leaves the acid, there is a NO3- ion, this means that it is left with a negative charge. To be able to form the molecule and make it stable we will need 2 NO3- ions.
So in total there are two nitrogen atoms