which transition by an electron will release the greatest amount of energy?\na\nb\nc\nd

Answer:

A.

Explanation:

Step1: Recall energy - level principle

The energy difference between levels is larger for larger - n to smaller - n transitions.

Step2: Analyze each option

Transition A is from $n = 4$ to $n = 1$, which has the largest change in principal quantum number among the given transitions. Since the energy of an electron in a hydrogen - like atom is given by $E=-\frac{13.6}{n^{2}}\text{ eV}$, the energy change $\Delta E = E_{final}-E_{initial}$, and the larger the difference in $n$ values for a transition from a higher to a lower level, the greater the energy released. Transitions B, C, and D have smaller differences in $n$ values compared to transition A.