The pH of a solution that turns red litmus blue is most likely: MCQ with Answer and Explanation

Explanation:
The thermite reaction involves aluminum powder reacting with iron(III) oxide to produce molten iron and aluminum oxide (2Al + Fe₂O₃ → Al₂O₃ + 2Fe). It is highly exothermic and is used for welding railway tracks and repairing metal structures in the field.

Explanation:
Fermentation of sugar (glucose) by yeast produces ethanol and carbon dioxide—new substances are formed, so it's a chemical change. Melting, boiling are physical state changes. Magnetization aligns domains but does not change chemical composition. Chemical changes involve breaking and forming of bonds. Indicators: gas evolution, color change, heat, precipitate.

Explanation:
Primary batteries are non-rechargeable; the chemical reaction that produces electricity cannot be reversed. The common dry cell (zinc-carbon battery) and alkaline batteries are primary cells. Lead-acid, Ni-Cd, and Li-ion are secondary (rechargeable) batteries where the reaction can be reversed by applying an external current.