The correct option is (c).
Explanation
Isotopes are atoms of the same element that possess the same atomic number (number of protons) but different mass numbers (number of neutrons). The behavior of isotopes is categorized based on their electronic structure and nuclear mass.
Statement-wise Analysis:
- Statement 1 is Incorrect: Chemical properties are governed by the electronic configuration, specifically the number of valence electrons. Since isotopes of the same element have the same number of electrons and identical electronic configurations, they exhibit identical chemical properties.
- Statement 2 is Correct: Physical properties such as density, boiling point, and melting point are influenced by the mass of the atom. Because isotopes differ in the number of neutrons, they have different atomic masses, which results in different physical properties.
- Statement 3 is Correct: The variation in physical properties is directly attributed to the difference in mass numbers. For example, heavier isotopes generally have higher boiling points and densities compared to lighter isotopes of the same element.
Key Takeaway:
Isotopes of an element share identical chemical properties (due to the same electron count) but possess distinct physical properties (due to different nuclear masses).