The correct option is A Similar chemical but different physical properties
Isotopes of an element have the same atomic number but different mass number. So, they have the same number of electrons but different number of neutrons. Chemical properties depend on the number of valence electrons. Thus, isotopes have similar chemical properties. The physical properties depend upon the atomic and the mass number of an element. Isotopes have different mass number i.e., different number of neutrons. Thus, they have different physical properties.