Statement I : During the setting of cement the structure has to be cooled by spraying . water. Statement II : The , constituents of cement undergo hydration during setting of cement and it is an exothermic reaction.

Statement I is true because during the setting of cement, the structure must be kept moist and cooled, often by spraying or fogging with water [t7]. This process, known as curing, prevents the concrete from drying too quickly and manages the internal temperature [t5][t9]. Statement II provides the correct scientific explanation: the chemical reaction between cement and water, known as hydration, is inherently exothermic [t1][t8]. This reaction releases significant heat, which can cause thermal stresses or cracking if not managed [t2][t3]. Spraying water facilitates evaporative cooling and ensures sufficient moisture remains available for the ongoing chemical reactions [t7][t9]. Therefore, Statement II is the correct explanation for the cooling requirement mentioned in Statement I, as the heat generated by the exothermic hydration must be dissipated to ensure structural integrity and optimal strength development [t1][t4].

Sources

1. [1] https://www.fhwa.dot.gov/pavement/concrete/pubs/hif18015.pdf
2. [2] https://www.sciencedirect.com/topics/engineering/cement-hydration-reaction