Although polonium is observed to have a higher ionization energy than bismuth, it is observed to have a lower ionization energy than tellurium. Explain.

• A. Polonium has a higher ionization energy than bismuth because it has a more effective nuclear charge. On the other hand, polonium has a lower ionization energy than tellurium due to a weaker shielding effect.
• B. Polonium has a higher ionization energy than bismuth because it has a less effective nuclear charge. On the other hand, polonium has a lower ionization energy than tellurium due to a weaker shielding effect.
• C. Polonium has a higher ionization energy than bismuth because it has a less effective nuclear charge. On the other hand, polonium has a lower ionization energy than tellurium due to a stronger shielding effect.
• D. Polonium has a higher ionization energy than bismuth because it has a more effective nuclear charge. On the other hand, polonium has a lower ionization energy than tellurium due to a stronger shielding effect.

Answer: (D)