Which subshell is likely to be filled after the rest of the subshells at a particular energy level?

The sublayer that is likely to be filled after the rest of the subshells at a specific energy level will be the "s" layer.

Explanation:

The sublayer that is likely to be filled after the rest of the subcases at a specific energy level will be the "s" layer. This is explained by the Pauling diagram.

Linus Pauling Diagram or Electronic Distribution Diagram is a model that assists in the configuration of the electrons of atoms and ions through energy sublevels. This diagram is based on the energy sublevels of the atom to organize the electrons. These are arranged from lowest to highest energy when the atom is in its ground state. The electrosphere of atoms is formed by 7 (seven) electronic layers, represented by the letters: K, L, M, N, O, P and Q. Each layer allows a maximum number of electrons and each layer has a number of sublevels.

The K layer has only one sublevel (s), which allows up to 2 electrons. This sublayer will likely fill after the rest of the subshells at a specific energy level.