Q1: A phosphatic fertiliser contains 16% P₂O₅. It could be

ANS:B - superphosphate

Superphosphate is a type of phosphatic fertilizer that is produced by treating phosphate rock with sulfuric acid. Here's an explanation of superphosphate:

1. Production: Superphosphate is manufactured through a chemical reaction between phosphate rock and sulfuric acid. The phosphate rock, which typically contains calcium phosphate minerals, is first ground into a fine powder. It is then reacted with sulfuric acid in a reactor vessel to produce soluble phosphate compounds.
2. Chemical Reaction: The reaction between phosphate rock and sulfuric acid can be represented by the following equation: Ca\textsubscript3(PO\textsubscript4)\textsubscript2+2H\textsubscript2SO\textsubscript4→Ca(H\textsubscript2PO\textsubscript4)\textsubscript2+2CaSO\textsubscript4Ca\textsubscript3(PO\textsubscript4)\textsubscript2+2H\textsubscript2SO\textsubscript4→Ca(H\textsubscript2PO\textsubscript4)\textsubscript2+2CaSO\textsubscript4 In this reaction, the phosphate rock is converted into soluble calcium dihydrogen phosphate (also known as monocalcium phosphate), which is readily available for plant uptake. The calcium sulfate formed during the reaction (commonly known as gypsum) is an inert byproduct.
3. Phosphorus Content: Superphosphate fertilizers typically contain phosphorus in the form of soluble phosphate ions, primarily as monocalcium phosphate (Ca(H2PO4)2). The phosphorus content is usually expressed in terms of phosphorus pentoxide (P2O5) content, with typical values ranging from 16% to 20%.
4. Nutrient Release: Once applied to the soil, superphosphate dissolves readily in soil moisture, releasing soluble phosphate ions that are immediately available for plant uptake. This rapid solubility makes superphosphate an effective source of phosphorus for promoting plant growth, especially in soils with low phosphorus availability.
5. Application: Superphosphate is commonly used as a phosphorus fertilizer in agriculture to improve soil fertility and promote healthy plant growth. It is suitable for a wide range of crops, including cereals, vegetables, fruits, and legumes. Superphosphate can be broadcast over the soil surface or incorporated into the soil during planting or cultivation.
6. Types of Superphosphate: There are two main types of superphosphate: single superphosphate (SSP) and triple superphosphate (TSP). SSP contains monocalcium phosphate as the primary phosphate source and is produced through a single reaction with sulfuric acid. TSP, on the other hand, is produced through multiple reactions with sulfuric acid, resulting in a higher phosphorus content and greater solubility compared to SSP.

Overall, superphosphate is a valuable phosphorus fertilizer that provides essential nutrients to plants, improves soil fertility, and enhances crop yields. Its ease of application, rapid nutrient release, and versatility make it a popular choice among farmers for promoting healthy plant growth and maximizing agricultural productivity.