Which element has no neutrons?

Hint:Let us first understand the structure of an atom. Every atom is made of three subatomic particles called electrons, protons and neutrons. The protons are positively charged and form the nucleus whereas electrons are negatively charged and are found orbiting around it. The neutrons are neutral that means they do not possess charge and is found in the nuclei of an atom

Complete answer:
We got to know the basics of these particles. Let us explore how to find out the number of electrons, protons and neutrons. Elements are usually represented as \[_Z^AX\]. In this notation Z is the atomic number, X is the symbol of an element whereas A is the mass number. Number of electrons and protons is equal to its atomic number and the number of neutrons is the difference between atomic number and atomic mass (Z-A). Let us take an example. The element Sodium is represented as \[_{11}^{23}Na\] which means the number of electrons and protons are 11 and neutrons are 12(23-11). In the same way hydrogen with atomic number 1 can be represented as \[_1^1H\]which means there are no neutrons as the atomic number and atomic mass are equal and their difference is zero. By the above explanation, we can conclude that Hydrogen is the only element which has no neutrons. Try to find out the number of neutrons of other elements as well.

Note:
There are other forms of an element called isotopes, isobars and isotones. The elements with the same atomic number and different mass number are isotopes. The elements with the same mass number but different atomic number are isobars and the one with the same number of neutrons are isotones.