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Periodic Classification (Class 11 — ~20% weight)

Modern periodic law, periodic trends in atomic radius, IE, EA, electronegativity.

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Q1 · Periodic Classification (Class 11 — ~20% weight) · MEDIUM
The first ionization energy generally increases across a period from left to right in the periodic table. Which of the following pairs shows an exception to this trend?
Q2 · Periodic Classification (Class 11 — ~20% weight) · EASY
The atomic radius of sodium is 186 pm, and the atomic radius of magnesium is 160 pm. Both elements are in period 3. What is the primary reason for this difference in atomic radius?
Q3 · Periodic Classification (Class 11 — ~20% weight) · HARD
Consider the following elements: F (fluorine), Cl (chlorine), O (oxygen), and S (sulfur). If the electron affinity values (in kJ/mol) are approximately: Cl = 349, O = 141, S = 200, and F = 328, which statement correctly explains why fluorine has a lower electron affinity than chlorine despite being more electronegative?
Q4 · Periodic Classification (Class 11 — ~20% weight) · EASY
Which of the following elements has the highest electronegativity?