Question

Which of the following pair is not isoelectronic species?
(At. no. $Sm, 62; Er, 68: Yb, 70: Lu, 71; Eu, 63: Tb , 65 ; Tm , 69$)

• A. $Sm ^{2+}$ and $Er ^{3+}$
• B. $Yb ^{2+}$ and $Lu ^{3+}$
• C. $Eu ^{2+}$ and $Tb ^{4+}$
• D. $Tb ^{2+}$ and $Tm ^{4+}$

Answer 1

Answer: (A), (D)

Correct answer is (a) $Sm ^{2+}$ and $Er ^{3+}$Correct answer is (d) $Tb ^{2+}$ and $Tm ^{4+}$