A black mineral (A) on heating in presence of air gives a gas (B). (A) and (B) are respectively:

Answer

To solve the question, we need to identify the black mineral (A) and the gas (B) produced when it is heated in the presence of air.

### Step-by-Step Solution:

1. **Identify the Black Mineral (A)**:
- The question states that we have a black mineral. A common black mineral that fits this description is **ferrous sulfide (FeS)**.

2. **Heating in Presence of Air**:
- When ferrous sulfide (FeS) is heated in the presence of air (which contains oxygen), it undergoes a chemical reaction.

3. **Chemical Reaction**:
- The reaction can be represented as follows:
\[ 4 \text{FeS} + 7 \text{O}_2 \rightarrow 2 \text{Fe}_2\text{O}_3 + 4 \text{SO}_2 \]
- Here, ferrous sulfide reacts with oxygen to produce ferric oxide (Fe₂O₃) and sulfur dioxide (SO₂).

4. **Identify the Gas (B)**:
- From the reaction, we can see that one of the products formed is **sulfur dioxide (SO₂)**. Therefore, the gas (B) produced is sulfur dioxide.

5. **Final Answer**:
- Thus, the black mineral (A) is **ferrous sulfide (FeS)** and the gas (B) is **sulfur dioxide (SO₂)**.

### Summary:
- A = Ferrous sulfide (FeS)
- B = Sulfur dioxide (SO₂)