What are the spectator ions in the reaction between aqueous nitric acid and ammonia?

Nitrate ions

Explanation:

Spectator ions are those ions which are present in the solution but do not take part in the chemical reaction occurring in the solution.

For finding the spectator ions we first need to look at the reaction between nitric acid and ammonia which is as follows -

HNO₃ (aq) + NH₃ (aq) → NH₄NO₃ (aq)

The ionic equation for this reaction will be -

H⁺ (aq) + NO₃⁻ (aq) + NH₃ (aq) → NH₄⁺ (aq) + NO₃⁻ (aq)

and thus the net ionic equation will be

H⁺ (aq) + NH₃ (aq) → NH₄⁺ (aq)

Here, we saw that though nitrate ions are formed in the solution but they are not taking part in the actual reaction. So for this reaction, NO₃⁻ ions are spectator ions.