$CuSO_4$ reacts with $KCN$ solution and forms:

Assign $A, B, C, D$ from the given type of reaction.
$CuSO_4 + NH_3$ (Excess) $\longrightarrow [Cu(NH_3)_4]^{2+}$

When Ethane-$1,2$-diamine is added progressively to an aqueous solution of Nickel $(II)$ chloride,the sequence of colour change observed will be :

Which of the following compounds after mixing cannot produce blue coloration?

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

The aqueous solution of a transition metal salt changes colour from pink to blue when concentrated hydrochloric acid is added to it. The change in colour is due to: