ANS:A - phosphoric acid

The reaction of dilute sulfuric acid with phosphate rock produces phosphoric acid. This reaction is a key step in the production of phosphoric acid, which is widely used in industry and agriculture. When phosphate rock (which typically contains calcium phosphate) reacts with sulfuric acid, it forms phosphoric acid and calcium sulfate (gypsum) as shown in the following chemical equation: \text{Ca\text{(PO}_4\text{)}}_2 + \text{H}_2\text{SO}_4 \rightarrow \text{CaSO}_4 + 2\text{H}_3\text{PO}_4 Phosphoric acid is a valuable intermediate chemical used in the production of fertilizers, detergents, food additives, and various other products. It is also an important component in the manufacture of superphosphate and triple superphosphate fertilizers, which are produced by further reacting phosphoric acid with phosphate rock or other materials.