Given below are two statements: Statement I: The decrease in metallic radius from element to element is greater in the actinoid series than in the lanthanoid series. Statement II: The 4f electrons have a poorer shielding effect compared to the 5f electrons. In the light of the above statements, choose the most appropriate answer from the options given below:

Step-by-step solution

Statement I is correct because the actinoid contraction is greater from element to element compared to the lanthanoid contraction. Statement II is incorrect because the 5f electrons have a poorer shielding effect than the 4f electrons. The poorer shielding by 5f electrons is the exact reason why the effective nuclear charge increases more significantly in actinoids, leading to the greater decrease in metallic radius mentioned in Statement I. Answer: Statement I is correct but Statement II is incorrect