Which of the following metals is extracted by the thermite process? MCQ with Answer and Explanation

Explanation:
Two reactants combine to form a single product, so combination (also called synthesis). No oxidation state change, so not redox. Decomposition is opposite.

Explanation:
Washing soda (Na₂CO₃) reacts with Ca²⁺ and Mg²⁺ ions in hard water to form insoluble carbonates: Ca²⁺ + Na₂CO₃ → CaCO₃↓ + 2Na⁺. Similarly MgCO₃. These precipitates are removed, softening the water. Ion exchange uses zeolites or resins. Boiling removes only temporary hardness. Distillation is expensive.

Explanation:
Across a period, nuclear charge increases while electrons are added to the same shell, leading to stronger attraction, so atomic radius decreases and ionization energy generally increases (with some exceptions like N to O due to half-filled stability). Metallic character decreases, non-metallic character increases. Electron affinity becomes more negative (increases in magnitude). Exam note: Ionization energy trend: Increases across period, decreases down group.