Hydrogen peroxide is used as a bleaching agent because it: MCQ with Answer and Explanation

Explanation:
Fermentation is the anaerobic breakdown of glucose by enzymes (zymase) in yeast to produce ethanol and CO₂: C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂. Esterification forms esters, saponification makes soap, hydrogenation adds H₂.

Explanation:
Portland cement is primarily made by heating a mixture of limestone (calcium carbonate) and clay (aluminosilicates) in a kiln at about 1450°C to form clinker. A small amount of gypsum is then added to the clinker to control the setting time, but limestone and clay are the main raw materials.

Explanation:
A positive catalyst increases reaction rate by lowering activation energy. Decreasing temperature generally slows reactions. Decreasing concentration reduces collision frequency, lowering rate. Larger pieces have less surface area, slower reaction. Other rate-increasing factors: increasing temperature, increasing pressure (for gases), using finely powdered solids, and light for photochemical reactions.