Question

What is the ground-state electron configuration of a neutral atom of hydrogen?

Answer 1

The lowest energy state.

Explanation:

1 electron in the S shell. 1s1 is the common notation, I think.

Answer 2

1 electron in the innermost shell, so configuration of just '1' (or '1s1' if considering orbitals).

Explanation:

Hydrogen in the ground state only has one electron, and since electrons "fill up" from the innermost electron shell/level outward, then this 1 electron is within the innermost shell.
To denote this as an electron configuration (using the 2-8-8 format) :
1

Considering s, p, d, and f orbitals the electron would likewise fill the s orbital of the first shell, so configuration would be:
1s1