Question

Poor shielding of nuclear charge by d or f-orbital electrons is responsible for which of the following facts?

• A. Atomic radius of Nb (4-1 series) is comparable to that of Ta (5-1 series)
• B. The $1^{st}$ ionisation energy of copper is less than that of zinc
• C. The value of electron gain enthalpy is more negative for sulphur than for oxygen.
• D. The $1^{st}$ ionisation energy for gold is greater than that of silver.

Answer 1

The correct option is B The $1^{st}$ ionisation energy of copper is less than that of zinc

Poor shielding of nuclear charge by d or f-orbital electrons is responsible for the main reason why $1^{st}$ ionization energy of copper is less than that of zinc.