Which element is indicated by the electron configuration [Rn] 7s² 5f¹¹?

The provided electron configuration [Rn] 7s² 5f¹¹ corresponds to an element that has its electron filling reaching the 5f subshell, which is characteristic of the actinides. In this configuration, the notation [Rn] indicates that the inner electronic structure follows that of radon, which is a noble gas with a completed outer electron shell. The notation 7s² indicates that there are two electrons in the 7s subshell.

The critical part of this configuration is the 5f¹¹, which signifies that there are eleven electrons in the 5f subshell. This number is essential for identifying the element since the actinides span from 5f¹ to 5f¹⁴. The specific element corresponding to 5f¹¹ is lawrencium (Lr), which is incorrectly matched to Californium in this case.

Californium (Cf) has an electron configuration ending with 5f¹⁰, meaning it has one fewer electron in the 5f subshell than indicated. The other options, Americium and Curium, along with Plutonium, also have fewer than eleven electrons in their respective 5f subs