Which of the following exhibits highest molar conductivity?

When ammonia is added to a cupric salt solution,the deep blue colour is observed; it is due to the formation of

The $IR$ stretching frequencies of free $CO$ and $CO$ in $[V(CO)_6]^-$,$[Cr(CO)_6]$ and $[Mn(CO)_6]^+$ are $2143 \, cm^{-1}$,$1860 \, cm^{-1}$,$2000 \, cm^{-1}$ and $2090 \, cm^{-1}$,respectively. Then the correct statement about metal carbonyls is:

The complex formed during the brown ring test of nitrate $(NO_3^-)$ ion is:

Which of the following correctly represents copper sulphate pentahydrate?

$PtCl_4 \cdot 6H_2O$ can exist as a hydrated complex. Its $1 \ m$ aqueous solution has a depression in freezing point of $3.72 \ ^\circ C$. Assuming $100\%$ ionization and $K_f \ (H_2O) = 1.86 \ ^\circ C \ kg \ mol^{-1}$,the correct formula for the complex is: