Which element does not have any neutron in it?

Hint : This question requires the knowledge of the presence of atomic particles that surround the nucleus of an atom of an element. Protons, electrons, and neutrons are the three basic types of particles that make up an atom. The mass of neutrons and protons is almost the same, whereas the mass of an electron is insignificant. A proton has a positive charge, whereas a neutron does not, and an electron has a negative charge.

Complete Step By Step Answer:
An atom with the same number of protons but a different number of neutrons is called an isotope of that element. The letter H stands for protium, which is the normal form of hydrogen. Protium is a one-proton element with no neutrons. Unlike the more common hydrogen atom, which has one proton, one electron, and no neutrons, deuterium has one neutron and one proton.
Protium is denoted by the letter H. It has an atomic number of 1 and a mass number of 1. Its nucleus has one proton and one electron in the 1s orbital. This isotope makes about 99.985 percent of naturally occurring hydrogen.
Because all hydrogen isotopes have one proton, they all have the same position in the periodic table. Because they have the same electrical arrangement, their chemical behavior is identical. They do, however, differ in physical qualities that are mass dependent.

Note :
This element has a total abundance of 156.25 ppm in the oceans, accounting for around 0.0156 percent of all hydrogen on the planet. The nucleus of deuterium, known as a deuteron, contains one proton and one neutron (mass number = 2), whereas the nucleus of the far more famous hydrogen isotope, protium, contains no neutrons.