Question

In isobars both chemical and physical property is different and in isotopes only chemical property is different why explain

Answer 1

Isobars : These are the atoms of different elements and their nuclei contains different no. of protons and neutrons but sum total of them is same.
Different chemical properties :
Since no. of protons in a isobars is different ,they have different no. of electrons that is different Atomic number. And Atomic no. is the fundamental property of an element on which chemical properties depends.
Thus isobars have different chemical properties.

Different physical properties :
Since they differ in no. of electrons they have different physical properties.
Chemical and physical properties depends upon the no. of electrons in an element.
Isotopes have similar chemical properties because isotopes of an element have the same number of electrons as an atom of that element. The electron arrangement is the same owing to same chemical properties. However they have different numbers of neutrons, which affects the mass number.