A hydrogen atom which has lost an electron contains

A hydrogen atom which has lost an electron contains only one proton. When an atom loses an electron, it becomes a positively charged ion. In the case of a hydrogen atom, which normally has one electron and one proton, the loss of an electron leaves only the proton in the nucleus. Protons are positively charged particles found in the nucleus of an atom, while electrons are negatively charged particles that orbit the nucleus. Since the hydrogen atom has lost an electron, the number of negatively charged particles no longer matches the number of positively charged particles, resulting in an ion with a positive charge. The other options listed, such as one neutron only, one proton and one neutron, or one proton, one electron, and one neutron, do not describe the structure of a hydrogen ion. A hydrogen ion contains only one positively charged proton and no electrons.