When a mixture of ammonium chloride and potassium dichromate was heated, a stable colourless gass (A) was evolved which did not support combustion, but magnesium continued to burn in it. The gas (A) reacted with calcium carbide in an electric furnace a solid (B) which was slowly hydrolysed by water forming an insoluble substance (C) and the solution of a substance (D) which turned Nessler's reagent brown. Identify substances (A) to (E) and explain all the reactions involved.

Explanation

To solve the problem step by step, we will identify the substances (A) to (E) and explain the reactions involved.

### Step 1: Heating Ammonium Chloride and Potassium Dichromate
When a mixture of ammonium chloride (NH4Cl) and potassium dichromate (K2Cr2O7) is heated, the following reaction occurs:

\[ 2 \text{NH}_4\text{Cl} + \text{K}_2\text{Cr}_2\text{O}_7 \rightarrow \text{Cr}_2\text{O}_3 + \text{N}_2 + \text{H}_2\text{O} + 2 \text{KCl} \]

From this reaction, we can see that nitrogen gas (N2) is produced, which is a colorless gas that does not support combustion. Therefore, we identify:
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