Which one among the following is the chemical formula of gypsum, which is an ingredient of cement? A. Ca2SiO4 B. $$CaS{O_4} \cdot 2{H_2}O$$ C. CaO D. $$CaS{O_4} \cdot 3{H_2}O$$

The correct answer is $\boxed{\text{B}}$. Gypsum is a mineral composed of calcium sulfate dihydrate, with the chemical formula $CaSO_4 \cdot 2H_2O$. It is a white, soft, and powdery mineral that is found in sedimentary rocks. Gypsum is used in a variety of applications, including as a building material, a fertilizer, and a food additive.

Option A is incorrect because it is the chemical formula of calcium silicate, which is a different mineral. Option C is incorrect because it is the chemical formula of calcium oxide, which is a different compound. Option D is incorrect because it is the chemical formula of calcium sulfate trihydrate, which is a different form of gypsum.