19. Rumus kimia senyawa kalsium sulfat dihidrat berikut ini adalah __ A. CaSO_(4).2H_(2)O B. CaSO_(4).3H_(2)O D. CaSO_(4).5H_(2)O C. CaSO_(4)4H_(2)O E. CaSO_(4).6H_(2)O

The correct answer is **A. **.Here's why:* **Calcium sulfate dihydrate** means that the compound contains one molecule of calcium sulfate ( ) and two molecules of water ( ). * The dot (.) in the formula indicates that the water molecules are associated with the calcium sulfate, forming a hydrate.Therefore, the correct chemical formula for calcium sulfate dihydrate is ** **.