Radioactive decay follows: MCQ with Answer and Explanation

Explanation:
Fluorine is the most electronegative element with a Pauling electronegativity of 3.98. Electronegativity increases across a period and decreases down a group. Thus, among the halogens, F > Cl > Br > I. Oxygen (3.44) is second. Electronegativity determines bond polarity. Because of its small size and high effective nuclear charge, fluorine strongly attracts bonding electrons. Noble gases are not assigned electronegativity values (except Kr, Xe).

Explanation:
Neutralization: Acid + Base → Salt + Water. Example: HCl + NaOH → NaCl + H₂O. It is a double displacement reaction. The pH of the resulting solution may be neutral, acidic, or basic depending on the strengths of the acid and base.

Explanation:
Cinnabar is HgS, the chief ore of mercury. Bauxite (Al), galena (Pb), magnetite (Fe). Mercury is extracted by roasting cinnabar in air: HgS + O₂ → Hg + SO₂.