Bohr's atomic model fails to explain the spectrum of: MCQ with Answer and Explanation

Explanation:
pH = -log[H⁺] = -log(10⁻⁴) = 4. The solution is acidic. pOH = 14 - pH = 10, so [OH⁻] = 10⁻¹⁰ M. pH scale ranges 0-14 (typically). pH < 7 acidic, pH = 7 neutral, pH > 7 basic. Pure water has [H⁺] = 10⁻⁷ M, pH=7.

Explanation:
Across a period, the number of electron shells remains the same, but the nuclear charge (protons) increases. The added electrons enter the same valence shell, so the effective nuclear attraction on the electrons increases, pulling them closer and shrinking the atomic radius. Down a group, radius increases due to addition of shells. Electron-electron repulsion alone does not account for the trend. Atomic mass generally increases across a period.

Explanation:
Acid rain is formed when sulfur dioxide (SO₂) and nitrogen oxides (NOx) emitted into the atmosphere (from burning fossil fuels) react with water, oxygen, and other chemicals to form sulfuric and nitric acids. These acids then fall to the ground as rain, damaging ecosystems.