Yes, a proton is the same as a hydrogen cation. In fact, a hydrogen cation (H+) is simply a proton that has lost its electron.
No, a proton cannot exist as a free particle. It is always found within an atom or molecule, where it is bound by the strong nuclear force.
A proton is positively charged, while a neutron is electrically neutral. Additionally, a proton is found in the nucleus of an atom, while a neutron is also found in the nucleus but has a slightly larger mass.
No, a proton and a hydrogen atom cannot be used interchangeably. A hydrogen atom consists of a proton and an electron, while a proton is just the positively charged particle. They have different properties and behaviors.
Yes, a hydrogen cation and a hydrogen ion refer to the same thing - a hydrogen atom that has lost its electron and has a positive charge.