Which of the following has the highest molar conductivity in solution?

Which are the dissimilarities between $CO$ and $PF_3$?

Silver chloride dissolves in excess of $NH_4OH$. The cation present in this solution is

In an ammoniacal solution,copper ions form the complex ion $[Cu(NH_3)_4]^{2+}$,but this does not occur in an acidic solution. The reason for this is:

$FeSO_4$ 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?

$A$ pink coloured aqueous solution of $Co(NO_3)_2$ turns blue on the addition of $HCl$ gradually. This colour change happens due to the formation of