An amorphous solid ‘A’ burns in air to form a gas ‘B’ which turns lime water milky. The gas is also produced as a by-product during roasting of sulphide ore. This gas decolourises acidified aq. `KMnO_(4)` solution. Identify the solid ‘A’ and the gas ‘B’ and write the reaction involved.
Write its any two uses.

Explanation

To solve the problem, we need to identify the amorphous solid 'A' and the gas 'B' produced during the burning of 'A'. We also need to write the reactions involved and provide two uses of the gas 'B'.

### Step-by-Step Solution:

1. **Identify the Amorphous Solid 'A':**
- The question states that an amorphous solid burns in air to produce a gas. Given the context, a likely candidate for solid 'A' is sulfur (S), which can exist in an amorphous form.

2. **Identify the Gas 'B':**
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