$AgCl$ dissolves in a solution of $NH_3$ but not in water because

$FeSO_4$ solution mixed with $(NH_4)_2SO_4$ solution in $1:1$ molar ratio gives the test of $Fe^{2+}$ ion,but $CuSO_4$ solution mixed with aqueous ammonia in $1:4$ molar ratio does not give the test of $Cu^{2+}$ ion. Explain why?

Which from the following is a correct stability order of complexes formed by metal ions if the ligand remains the same?

The hydrated $Cu^{2+}$ ion is:

When $0.1 \ mole$ of $CoCl_3(NH_3)_5$ is treated with excess of $AgNO_3$,$0.2 \ mole$ of $AgCl$ are obtained. The conductivity of the solution will correspond to:

$50 \, mL$ of $0.2 \, M$ solution of a compound with empirical formula $CoCl_3 \cdot 4NH_3$ on treatment with excess of $AgNO_{3(aq)}$ yields $1.435 \, g$ of $AgCl$. Ammonia is not removed by treatment with concentrated $H_2SO_4$. The formula of the compound is: