ANS:C - either (a) or (b)

Sulphuric Acid (H2SO4):

1. • Sulphuric acid is a strong mineral acid with the chemical formula H2SO4. It is one of the most widely used industrial chemicals, with applications in various industries, including fertilizer production, chemical manufacturing, and metal processing.
   • In the context of leaching phosphate rock, sulphuric acid is commonly used to extract phosphorus in the form of phosphoric acid. The reaction involves treating phosphate rock with concentrated sulphuric acid, leading to the formation of soluble phosphate compounds, such as monocalcium phosphate (Ca(H2PO4)2) or soluble phosphates.
   • Sulphuric acid is preferred for phosphate rock leaching due to its high solubility, aggressive acidic properties, and ability to form soluble phosphate compounds efficiently. It helps dissolve the phosphate minerals in the rock and facilitates the extraction of phosphorus, which is essential for the production of phosphoric acid and phosphate fertilizers.
2. Hydrochloric Acid (HCl):
   • Hydrochloric acid is another strong mineral acid with the chemical formula HCl. It is widely used in various industrial processes, including metal cleaning, pickling, and chemical synthesis.
   • While hydrochloric acid can theoretically be used for leaching phosphate rock, it is less commonly employed compared to sulphuric acid. This is primarily due to factors such as cost, availability, and reaction efficiency.
   • Hydrochloric acid may react with some phosphate minerals, but it may not be as effective or efficient as sulphuric acid in terms of phosphate extraction and phosphoric acid production. Additionally, hydrochloric acid can form insoluble calcium chloride (CaCl2) salts during the reaction, which may interfere with the extraction process and require additional purification steps.
   • Overall, while hydrochloric acid can be used for certain leaching applications, sulphuric acid is generally preferred for phosphate rock leaching due to its higher solubility, reactivity, and suitability for phosphoric acid production.

In summary, both sulphuric acid and hydrochloric acid are strong mineral acids that can potentially be used for leaching phosphate rock to produce phosphoric acid. However, sulphuric acid is more commonly employed in industrial processes due to its superior solubility, reactivity, and efficiency in phosphate extraction.