Trends in Period 3: Effective Nuclear Charge and Ionic Radii Steps: - Nuclear charge increases across Period 3 as protons are added, with constant electron shells. - Shielding by inner electrons remains constant, increasing effective nuclear charge on outer electrons. - This pulls electrons closer, decreasing atomic radii; for common ions, cation radii decrease left to right, but anion radii are larger overall. - Statements evaluated: A partially true for cations but not overall; B false on shielding; C true on nuclear pull. Why D is correct: - D selects the accurate statements (likely A and C or C only), aligning with increasing effective nuclear charge per Coulomb's law, where Z_eff = Z - σ (σ constant). Why the others are wrong: - A: Ionic radii do not steadily decrease; anions (e.g., Cl⁻ at 181 pm) are larger than cations (e.g., Na⁺ at 102 pm). - B: Shielding by inner electrons is constant, not decreasing, as core electron count unchanged. - C: Correct, but if D excludes it, not applicable here. Not enough information on full D option. Final answer: …