Verified Solution • 2025–26 Session moderate

QJEEM22Ch8dd0: JEE Main 2022 Chemistry - Class 12 JEEM22Ch8dd0 Solution: Which of the following pair is not isoelectronic species? (At.…

Which of the following pair is not isoelectronic species?

(At. no. Sm, 62; Er, 68; Yb, 70; Lu, 71; Eu, 63; Tb, 65; Tm, 69)

Multiple Choice Options

  • A Sm2+\mathrm{Sm}^{2+} and Er3+\mathrm{Er}^{3+}
  • B Yb2+\mathrm{Yb}^{2+} and Lu3+\mathrm{Lu}^{3+}
  • C Eu2+\mathrm{Eu}^{2+} and Tb4+\mathrm{Tb}^{4+}
  • D Tb2+\mathrm{Tb}^{2+} and Tm4+\mathrm{Tm}^{4+}

Step-by-Step Verified Solution

Species having same number of electrons are isoelectronic

Tb⟶65 Tb+2⟶63 electrons Tm⟶69 Tm+4⟶65 electrons }\left.\begin{array}{l}\mathrm{Tb} \longrightarrow 65 \mathrm{~Tb}^{+2} \longrightarrow 63 \text { electrons } \\ \mathrm{Tm} \longrightarrow 69 ~\mathrm{Tm}^{+4} \longrightarrow 65 \text { electrons }\end{array}\right\} not isoelectronic

Sm+2⟶60 electrons Er+3⟶65 electrons }\left.\begin{array}{c}\mathrm{Sm}^{+2} \longrightarrow 60 \text { electrons } \\ \mathrm{Er}^{+3} \longrightarrow 65 \text { electrons }\end{array}\right\} not isoelectronic

Related Learning Resources & Exam Preparation

JEE Main PYQ Question Bank
Browse year-wise authentic previous years' questions with solutions
Authentic CBT Mock Tests
Simulate official exam environment with live timer and percentile scoring