Periodic trends in halogens Steps:

• Astatine is below iodine in group 17 of the periodic table.
• Electronegativity decreases down a group due to increasing atomic size and shielding.
• For halogens, reactivity as oxidizing agents decreases down the group as bond strength in X-X increases.
• Thus, astatine is less electronegative with lower reactivity than iodine.

Why C is correct:

• Periodic trend: Electronegativity and reactivity decrease down group 17, as valence electrons are farther from the nucleus.

Why the others are wrong:

• A: Astatine is not more electronegative; electronegativity decreases down the group.
• B: Reactivity is lower, not higher, for astatine.
• D: Astatine is not more electronegative; it has lower electronegativity.

Final answer: C