The correct answer is option 2, which states that only statement 1 is correct.

Let`s dissect each option to understand why this is the correct answer:

1. Isotopes: Atoms with the same atomic number but different atomic mass. This statement is correct. Isotopes are atoms of the same element that have different numbers of neutrons, resulting in different atomic masses. The atomic number is determined by the number of protons, which remains the same in isotopes.

2. Isobars: Atoms with the same number of neutrons but different atomic number. This statement is incorrect. Isobars are atoms of different elements that have the same mass number, which is the sum of protons and neutrons. The atomic number, which is the number of protons, is different in isobars.

3. Isotones: Atoms with the same mass number but different atomic number. This statement is incorrect. Isotones are atoms of different elements that have the same number of neutrons, but their atomic numbers are different.

Therefore, only statement 1, which defines isotopes correctly, is matched correctly.