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MHT CET202613 April 2026Morning ShiftChemistryStructure of AtomActual

Which of the following pairs represents isobars?

Options

  1. A³ He ₂ and ⁴ He ₂
  2. B²⁴ Mg ₁₂ and ²⁵ Mg ₁₂
  3. C⁴⁰ K ₁₉ and ⁴⁰ Ca ₂₀
  4. D⁴⁰ K ₁₉ and ³⁹ K ₁₉

Correct answer

C. ⁴⁰ K ₁₉ and ⁴⁰ Ca ₂₀

Step-by-step solution

Isobars are atoms of different elements having the same mass number but different atomic numbers. In the pair ⁴⁰ K ₁₉ and ⁴⁰ Ca ₂₀ , both have the same mass number 40 but different atomic numbers 19 and 20 respectively. Thus, they represent a pair of isobars. Answer: ⁴⁰ K ₁₉ and ⁴⁰ Ca ₂₀

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