Assertion (A): Isotones have different chemical properties but similar nuclear properties.
Reason (R): Chemical properties depend on electrons, while nuclear properties depend on neutrons.

⁵⁶Fe and ⁵⁷Co are isotones.

• Isotones are nuclei that have the same number of neutrons but different numbers of protons (atomic numbers).
• ⁵⁶Fe (iron) has an atomic number of 26, so the number of protons is 26. The mass number is 56, so the number of neutrons is 56 − 26 = 30.

Since both nuclei have 30 neutrons, ⁵⁶Fe and ⁵⁷Co are isotones.

They have the same number of neutrons but different proton numbers.

• This statement is true because, as shown above, they both have 30 neutrons but differ in their proton numbers (26 for iron and 27 for cobalt).