Answer
$\Delta E$ would be positive in this electronic transition.
Work Step by Step
The change of energy $(\Delta E)$ is:
- positive when the electron moves from a lower state (lower energy) to a higher state (higher energy).
- negative when the electron moves from a higher state (higher energy) to a lower state (lower energy).
The electron here moves from n = 4 to n = 9, meaning that it moves from a lower state to a higher state.
Therefore, $\Delta E$ would be positive.
