ANS:A - orthophosphoric acid

The reaction of phosphate rock with 98% H2SO4 (sulfuric acid) produces orthophosphoric acid. This reaction is a part of the process for producing phosphoric acid, also known as orthophosphoric acid, which is a key ingredient in the production of fertilizers, detergents, and various other industrial products. When phosphate rock reacts with sulfuric acid, it forms orthophosphoric acid along with calcium sulfate (gypsum) as a by-product. So, the correct option is: orthophosphoric acid Orthophosphoric acid, also known as phosphoric acid, is a colorless, odorless liquid with the chemical formula H3PO4. It is one of the most important and widely used phosphorus-containing compounds in industry and agriculture. Here are some key points about orthophosphoric acid:

1. Chemical Structure: Orthophosphoric acid is a triprotic acid, meaning it can donate three protons (H⁺ ions) in solution. It consists of one phosphorus atom (P) surrounded by four oxygen atoms, three of which are bonded to hydrogen atoms. The structure can be represented as H3PO4.
2. Production: Orthophosphoric acid is produced industrially through the reaction of phosphate rock (usually calcium phosphate) with sulfuric acid (H2SO4). This process, known as the wet process or the thermal process, produces a concentrated solution of phosphoric acid, which can be further purified and concentrated through various methods.
3. Applications:
   • Fertilizers: Orthophosphoric acid is a primary ingredient in the production of phosphate fertilizers, such as superphosphate and triple superphosphate, which are essential for promoting plant growth and improving crop yields.
   • Food and Beverage Industry: Orthophosphoric acid is used as an acidulant and flavor enhancer in the food and beverage industry. It is commonly found in soft drinks, processed foods, and various food additives.
   • Detergents and Cleaners: Orthophosphoric acid is used in detergents and cleaners as a chelating agent and pH adjuster. It helps to remove mineral deposits, rust stains, and scale from surfaces.
   • Water Treatment: Orthophosphoric acid is employed in water treatment processes to inhibit corrosion and scale formation in industrial equipment, boilers, and pipelines.
   • Chemical Synthesis: Orthophosphoric acid is used as a precursor in the synthesis of various phosphorus-containing compounds, including pharmaceuticals, flame retardants, and specialty chemicals.
4. Safety Considerations: Orthophosphoric acid is corrosive and can cause severe burns upon contact with skin, eyes, or mucous membranes. Proper handling procedures, including the use of personal protective equipment and appropriate safety measures, are essential when working with orthophosphoric acid.