_70Yb^2+ and _71Lu^3+ Lanthanoid ions. .............

The correct answer is Option (2) → Diamagnetic and diamagnetic respectively

An ion is paramagnetic if it has one or more unpaired electrons and diamagnetic if all its electrons are paired. For lanthanoid ions this depends on the number of 4f electrons, which is found from the atomic number and the charge.

• Yb²⁺: Yb (Z = 70) is [Xe]4f¹⁴6s²; losing the two 6s electrons gives \( \ce{Yb^{2+}} \): [Xe]4f¹⁴. All seven 4f orbitals are full, so there are no unpaired electrons: diamagnetic.

• Lu³⁺: Lu (Z = 71) is [Xe]4f¹⁴5d¹6s²; losing the two 6s electrons and the 5d electron gives \( \ce{Lu^{3+}} \): [Xe]4f¹⁴. Again a completely filled 4f subshell: diamagnetic.

Both ions have the configuration 4f¹⁴, so both are diamagnetic.