Among the following,the $\pi$-acid ligand is

Which equilibrium can be described as an acid-base reaction using the Lewis acid-base definition but not using the Bronsted-Lowry definition?

The colour of $CoCl_3 \cdot 5NH_3 \cdot H_2O$ is

When concentrated sulphuric acid is added slowly to a solution of ferrous sulphate containing nitrate ion,a brown coloured ring is formed. The composition of the ring is

The correct increasing order of stability of the complexes based on $\Delta_o$ value is $:$
$I. \ [Mn(CN)_6]^{3-}$
$II. \ [Co(CN)_6]^{4-}$
$III. \ [Fe(CN)_6]^{4-}$
$IV. \ [Fe(CN)_6]^{3-}$

Which of the following complexes does not give a precipitate with $AgNO_3$ solution?