Which option describe a similarity and a difference between isotope and an element

Answer:Isotopes are chemical elements which differ in neutron number, and consequently in nucleon number. All isotopes of a given element have the equal no of protons but different numbers of neutrons. The total number of protons is called atomic number and is equal to the number of electrons in an atom. Each atomic number identifies a special element. An atom of a given element may have a wide range in its number of neutrons. The number of nucleons (both protons and neutrons) in the nucleus is nothing but the mass number, and each isotope of a given element has a different mass number.