Identify A, B, C, D and E.
A while substance A reacts with dilute `H_2SO_4` to produce a colourless gas B and a colourless solution C. The reaction between B and acidified `K_2Cr_2O_7` solution produces a green solution and slightly coloured precipitate D. The substance D burns in air to produce a gas E which reacts with B to yield D and a colourless liquid. Anhydrous copper sulphate is turned blue on adiition of this colourless liquid. Addition of aqueous `NH_3` or `NaOH` to C produces first a precipitate

Explanation

To solve the problem, we will identify the substances A, B, C, D, and E step by step based on the information provided in the question and the video transcript.

### Step 1: Identify Substance A
Substance A is a white solid that reacts with dilute sulfuric acid (H₂SO₄). The reaction produces a colorless gas and a colorless solution.

**Reaction:**
\[ \text{A} + \text{H}_2\text{SO}_4 \rightarrow \text{B} + \text{C} \]

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