Which part of a helium atom is positively charged?

(1) electron (3) nucleus

(2) neutron (4) orbital

The correct answer is 3.

In any atom, the nucleus will be positively charged because the only ions in the nucleus are neutrons, which have a neutral charge, and protons, which have a positive charge.

Electrons are negatively charged, and they are in the orbital, thus making the orbital negatively charged.