No reaction will occur when NiCl₂(aq.) is added to a test tube containing Zn(NO₃)₂(aq). As to a reaction to occur between two solutions that most probably undergoes a double displacement reaction , it has to meet the following requirements:
1) Precipitate formation
2) Gas generation
3) formation of a non-dissociating compound
But in the reaction of NiCl₂(aq) with Zn(NO₃)₂(aq), no above requirement is met, so no reaction takes place.
NiCl₂(aq.) + Zn(NO₃)₂(aq). ------>No reaction