Explanation:

Na2HPO4 is the sodium salt of dihydrogen phosphate, which is a weak acid. When Na2HPO4 is dissolved in water, it undergoes hydrolysis, which is a chemical reaction in which water molecules react with the salt to produce an acid and a base. In the case of Na2HPO4, the hydrolysis reaction can be represented as follows:

Na2HPO4 + H2O ⇌ NaH2PO4 + NaOH

In this reaction, Na2HPO4 donates a proton (H+) to water, which results in the formation of hydronium ions (H3O+) and hydroxide ions (OH-). The hydroxide ions produced in this reaction make the solution basic.