On heating, a salt gives a gas which turns lime water milky and an acidified dichromate solution green. The salt may be:

Options

A. carbonate
B. sulphide
C. sulphate
D. sulphite

Answer

To solve the question regarding the salt that produces a gas which turns lime water milky and an acidified dichromate solution green upon heating, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Gases Produced**:
- When a salt is heated, it can produce different gases. The two gases of interest in this scenario are carbon dioxide (CO₂) and sulfur dioxide (SO₂).
- CO₂ turns lime water milky, while SO₂ can turn an acidified dichromate solution green.

2. **Understanding the Reactions**:
- Lime water (a solution of calcium hydroxide) turns milky due to the formation of calcium carbonate (CaCO₃) when CO₂ is bubbled through it.
- Acidified dichromate solution (usually potassium dichromate in sulfuric acid) turns green when it is reduced by SO₂.

3. **Determine the Source of SO₂**:
- The gas that can turn the acidified dichromate solution green is SO₂. This gas is typically produced from the heating of metal sulfides.
- Therefore, we need to consider salts that contain sulfide ions (S²⁻), as these will yield SO₂ upon heating.

4. **Conclusion**:
- The salt that fits the criteria of producing a gas that turns lime water milky (either CO₂ or SO₂) and reduces acidified dichromate solution to green (which is specifically SO₂) is a metal sulfide.
- Thus, the answer to the question is that the salt may be a sulfide.

### Final Answer:
The salt may be a **sulfide**.

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