Correct option is B
The correct answer is: (b) ⁴⁰₁₉K and ⁴⁰₂₀Ca
- Isobars are atoms of different elements that have the same mass number but different atomic numbers.
- In option (b), ⁴⁰₁₉K (Potassium) and ⁴⁰₂₀Ca (Calcium) both have mass number 40 but different atomic numbers, fulfilling the condition for isobars.
Information Booster:
• • Isobars have same mass number (A) and different atomic number (Z).
• • They are chemically different due to different proton counts.
• • Examples: ¹⁴₆C and ¹⁴₇N, ⁴⁰₁₈Ar and ⁴⁰₂₀Ca.
• • Isobars are useful in nuclear reactions and radioactive studies.
• • Isotopes have the same atomic number but different mass numbers.
• • The term 'isobar' was introduced by Aston, developer of the mass spectrograph.
Additional Information:
• • Option (a): ⁴⁰₁₉K and ³⁹₁₉K – Incorrect: Same atomic number → isotopes.
• • Option (b): ⁴⁰₁₉K and ⁴⁰₂₀Ca – Correct: Same mass number, different atomic number → isobars.
• • Option (c): ³₂He and ⁴₂He – Incorrect: Same atomic number → isotopes.
• • Option (d): ²⁴₁₂Hg and ²⁵₁₂Mg – Incorrect: Hg’s atomic number is 80, not 12; also not same mass number.
