Here's why:

* Protons are subatomic particles that carry a positive electrical charge.

* Hydrogen is the simplest atom, consisting of only one proton and one electron.

* The electron carries a negative charge, equal in magnitude to the proton's positive charge.

* Normally, a hydrogen atom is electrically neutral because the positive charge of the proton is balanced by the negative charge of the electron.

* However, when the electron is removed, the hydrogen nucleus is left with only the proton, making it positively charged.

This positive charge is what makes the hydrogen nucleus, also known as a hydrogen ion (H+), very reactive and important in many chemical reactions.