Eutrophication in water bodies is primarily caused by an excess of: MCQ with Answer and Explanation

Explanation:
Chlorofluorocarbons (CFCs), used in refrigerants and aerosols, reach the stratosphere where UV radiation breaks them down, releasing chlorine atoms. These chlorine atoms catalytically destroy ozone (O₃) molecules, leading to the depletion of the ozone layer, particularly over Antarctica.

Explanation:
C₂H₄ (ethene) is an alkene with a carbon-carbon double bond, thus unsaturated. The general formula CnH₂n indicates an alkene or cycloalkane. C₃H₈, C₄H₁₀, C₅H₁₂ follow CnH₂n+2 and are saturated alkanes. Unsaturated compounds undergo addition reactions, whereas saturated undergo substitution.

Explanation:
Rutherford's gold foil experiment (1911) showed that most of the atom is empty space with a dense positively charged nucleus. Thomson proposed the plum pudding model; Bohr gave quantized orbits; Dalton gave solid sphere model.