In the following reaction , identify the compound / reaction condition represented by A and B
`PbS overset("Heat in air") to A A + PbS overset(B) to Pb + SO_(2)`

Explanation

To solve the question, we need to identify the compounds or reaction conditions represented by A and B in the given reactions involving lead sulfide (PbS).

### Step-by-Step Solution:

1. **Identify the first reaction**:
The first reaction given is:
\[
\text{PbS} \overset{\text{Heat in air}}{\rightarrow} A
...