Question

Lanthanide contraction is caused due to:

• A. the appreciable shielding on outer electrons by $5d$ electrons from the nuclear charge
• B. he appreciable shielding on outer electrons by $4f$ electrons from the nuclear charge
• C. the imperfect shielding of outer electrons by $4f$ electrons from the nuclear charge
• D. the same effective nuclear charge from $Ce$ to $Lu$

Answer 1

The correct option is C the imperfect shielding of outer electrons by $4f$ electrons from the nuclear charge

Lanthanide contraction is caused due to poor shielding of the $5s$ and $5p$ electrons by the $4f$ electrons.