Which of the following is a chemical uptake form of phosphorus?

The correct answer is H2PO4-. This form of phosphorus, known as dihydrogen phosphate, is a significant chemical species that plants can readily uptake from the soil. In the context of soil chemistry and plant nutrition, H2PO4- is one of the most accessible forms of phosphorus for plants, particularly under acidic to neutral pH conditions.

Plants primarily absorb phosphorus in its ionic forms, and H2PO4- is favored in many soil environments because it is soluble in water and available for plant roots to absorb. Its chemical structure allows for effective interaction with plant roots, making it a crucial form of phosphorus for plant growth.

Other forms of phosphorus mentioned, such as HPO4- and PO4-3, while also involved in phosphorus chemistry, are less favorable for plant uptake compared to H2PO4-. P2O5, on the other hand, refers to a phosphorus oxide and is not directly a chemical form of phosphorus that plants uptake; rather, it represents phosphorus as it would be found in fertilizers and requires conversion in the soil to more plant-accessible forms.