It helps to write out the chemical reactions
CuCl2(aq) + 2AgNO3(aq) ==>Cu(NO3)2(aq) + 2AgCl(s)
Copper(II) nitrate will be deep blue in color and AgCl will be a white precipitate
HCl(aq) + AgNO3(aq) ==> AgCl(s) + HNO3(aq)
This will be a clear solution with a white precipitate.
A hypothesis to account for the reaction product? There is no hypothesis. It is a double replacement/displacement reaction where a precipitate of silver chloride is formed.