While a substance is undergoing a change of state, the temperature of the body remains the ………..

Explanation

### Step-by-Step Solution:

1. **Understanding the Change of State**:
When a substance changes from one state to another (for example, from solid to liquid or liquid to gas), it undergoes a phase transition.

**Hint**: Remember that common phase changes include melting (solid to liquid) and boiling (liquid to gas).

2. **Temperature During Phase Change**:
...