colourless salt `(A) underset(740^(@)C) overset(Delta)to (B) +(C ) overset(Cu^(2+),Delta)to` blue coloured bead (D)
Identify the compound (A),(B),(C ) and (D).

Explanation

To solve the problem, we need to identify the compounds A, B, C, and D based on the reactions described in the question. Let's break it down step by step.

### Step 1: Identify Compound A
The question states that a colorless salt (A) is heated at 740°C. The compound that fits this description is **Sodium Tetraborate Decahydrate**, commonly known as **Borax**. Its chemical formula is:
\[ \text{Na}_2\text{B}_4\text{O}_7 \cdot 10\text{H}_2\text{O} \]
Thus, we identify:
- **Compound A**: \(\text{Na}_2\text{B}_4\text{O}_7 \cdot 10\text{H}_2\text{O}\)

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