Atomic Structure and Periodic Table — Prelims Questions

Consider the following statements regarding periodic trends: 1. Atomic radius generally decreases across a period due to increasing effective nuclear charge. 2. Ionization energy generally increases down a group due to increased shielding effect. 3. Electronegativity generally increases across a period due to decreasing atomic size. Which of the statements given above is/are correct?

Which of the following atomic models failed to explain the stability of the atom and the line spectrum of hydrogen? (A) Dalton's Atomic Theory (B) Thomson's Plum Pudding Model (C) Rutherford's Nuclear Model (D) Bohr's Model

Which of the following statements about electronic configuration rules is INCORRECT? (A) The Aufbau principle states that electrons fill orbitals in order of increasing energy. (B) The Pauli exclusion principle states that no two electrons in an atom can have the same set of four quantum numbers. (C) Hund's rule of maximum multiplicity states that electrons pair up in degenerate orbitals only after all orbitals of that subshell are singly occupied with parallel spins. (D) Chromium (Z=24) has an electronic configuration of [Ar] 3d⁴ 4s².

Consider the following elements: Na, Mg, Al, Si. Which of the following correctly represents the order of increasing first ionization energy?

Which of the following statements best describes the 'lanthanide contraction' and its consequence? (A) It is the increase in atomic and ionic radii across the lanthanide series, leading to larger sizes for elements following them. (B) It is the steady decrease in atomic and ionic radii across the lanthanide series, resulting in similar sizes for elements in the 5d and 4d series. (C) It is the decrease in metallic character across the lanthanide series, making them less reactive. (D) It is the increase in ionization energy across the lanthanide series, making them harder to oxidize.