DP Chemistry (first assessment 2025)
Question 19M.1A.SL.TZ2.5
| Date | May 2019 | Marks available | [Maximum mark: 1] | Reference code | 19M.1A.SL.TZ2.5 |
| Level | SL | Paper | 1A | Time zone | TZ2 |
| Command term | Question number | 5 | Adapted from | N/A |
5.
[Maximum mark: 1]
19M.1A.SL.TZ2.5
Which of the following transitions in the hydrogen atom emits the least energy?
A. n = 2 to n = 1
B. n = 3 to n = 1
C. n = 4 to n = 2
D. n = 4 to n = 3
[1]
Markscheme
D
Examiners report
81 % of the candidates identified the transition the emits the least energy in the given four transitions in the hydrogen atom (which was n=4 to n=3). The most commonly chosen distractor was A (n=2 to n=1) which means these candidates did not realize that the energy levels in the hydrogen atom converge at higher energy.
Syllabus sections
Structure 1. Models of the particulate nature of matter » Structure 1.3—Electron configurations » Structure 1.3.2—The line emission spectrum of the hydrogen atom. The line emission spectrum of hydrogen provides evidence for the existence of electrons in discrete energy levels, which converge at higher energies. Describe the emission spectrum of the hydrogen atom, including the relationships between the lines and energy transitions to the first, second and third energy levels.