Cement sets into a hard mass when mixed with water due to:
A. Evaporation of water
B. Polymerization
C. Hydration and crystallization of silicates and aluminates
D. Oxidation
Answer: Option C
Solution (By JKSSB Mock Tests)
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:
Terylene is a synthetic fiber belonging to the polyester family. Chemically, it is polyethylene terephthalate (PET), formed by the condensation polymerization of ethylene glycol and terephthalic acid. It is widely used in textiles, plastic bottles, and recording tapes.
Explanation:
In both electrolytic and galvanic cells, oxidation occurs at the anode (AN OX). The anode is positive in electrolytic cells, negative in galvanic. Reduction at cathode (RED CAT). Electroplating: object at cathode, dissolution at anode.
Explanation:
Crystallization separates a pure solid from a solution by cooling or evaporating the solvent. Impurities remain in the mother liquor. Example: purifying copper sulfate. Distillation for liquids; filtration for insoluble solids.
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