Which one of the following,when dissolved in water,gives a coloured solution in a nitrogen atmosphere?

Which of the following compositions is found in dental amalgam alloys?

Which compound of zinc is white in the cold state and turns yellow in the hot state?

The metal that does not give the borax bead test is

When a chromite ore $(A)$ is fused with sodium carbonate in free excess of air and the product is dissolved in water,a yellow solution of compound $(B)$ is obtained. After treatment of this yellow solution with sulphuric acid,compound $(C)$ can be crystallised from the solution. When compound $(C)$ is treated with $KCl$,orange crystals of compound $(D)$ crystallise out. Identify $A$ to $D$ and also explain the reactions.

Preparation of potassium permanganate from $MnO_2$ involves a two-step process in which the $1^{st}$ step is a reaction with $KOH$ and $KNO_3$ to produce: