Which of the following represents the ground-state electron configuration of a transition metal ion?
[Ar]4s23d4[\text{Ar}] 4\text{s}^2 3\text{d}^4[Ar]4s23d4
[Ar]3d6[\text{Ar}] 3\text{d}^6[Ar]3d6
[Ar]4s23d9[\text{Ar}] 4\text{s}^2 3\text{d}^9[Ar]4s23d9
[Ar]4s13d5[\text{Ar}] 4\text{s}^1 3\text{d}^5[Ar]4s13d5
33 exam-style questions on AQA A Level Chemistry Atomic structure, covering Fundamental particles, Mass number and isotopes, and Electron configuration. Each one has a worked solution and a mark scheme showing where the marks go.