Cement sets into a hard mass when mixed with water due to:
A. Oxidation
B. Evaporation of water
C. Hydration and crystallization of silicates and aluminates
D. Polymerization
Answer: Option C
Solution (By JKExamLibrary)
Cement undergoes hydration reactions: water reacts with cement compounds (C₃S, C₂S, C₃A) to form complex hydrated silicates and aluminates (e.g., C-S-H gel) along with Ca(OH)₂. This process causes setting and hardening, forming a rigid, rock-like mass. It is exothermic. Gypsum controls initial setting. Proper curing is necessary for strength development.
Explanation:
Urea (CO(NH₂)₂) is a nitrogenous fertilizer with the highest nitrogen content (about 46%). Superphosphate provides phosphorus, muriate of potash (KCl) provides potassium, and gypsum (CaSO₄·2H₂O) is a soil conditioner providing calcium and sulfur, not primary NPK nutrients.
Explanation:
Amylase is an enzyme (biological catalyst) that breaks down starch. Platinum, V₂O₅, and iron are inorganic chemical catalysts. Enzymes are proteins, highly specific, and work under mild conditions.
Explanation:
Ethanol, commonly known as ethyl alcohol, has the chemical formula C₂H₅OH. Methanol is CH₃OH. Acetic acid (ethanoic acid) is CH₃COOH, and propionic acid is C₂H₅COOH. Ethanol is widely used as a solvent, in alcoholic beverages, and as a biofuel.
No comments yet. Be the first to start the discussion!