Overview:
In this aqueous solution, we have a mixture of two salts: KH2PO4 and K2HPO4. Both salts are composed of potassium ions (K+) and phosphate ions (PO4^3-). The concentration of KH2PO4 is 0.3 mol/L, while the concentration of K2HPO4 is 0.0150 mol/L.
To understand the behavior of this solution, we need to consider the dissociation of these salts in water and the resulting ions.

Dissociation of KH2PO4:
KH2PO4 dissociates in water to produce potassium ions (K+) and hydrogen phosphate ions (HPO4^2-). The dissociation reaction can be represented as follows:
KH2PO4 ⇌ K+ + H2PO4^-
The concentration of potassium ions (K+) will be equal to the initial concentration of KH2PO4, which is 0.3 mol/L. The concentration of hydrogen phosphate ions (HPO4^2-) will also be 0.3 mol/L.

Dissociation of K2HPO4:
K2HPO4 dissociates in water to produce potassium ions (K+) and phosphate ions (PO4^3-). The dissociation reaction can be represented as follows:
K2HPO4 ⇌ 2K+ + HPO4^2-
The concentration of potassium ions (K+) will be equal to twice the initial concentration of K2HPO4, which is 0.0150 mol/L. Therefore, the concentration of potassium ions (K+) will be 0.0300 mol/L. The concentration of phosphate ions (PO4^3-) will be 0.0150 mol/L.

Overall solution:
When we combine the solutions of KH2PO4 and K2HPO4, the resulting solution will contain the following ions:
- Potassium ions (K+): The concentration of K+ will be the sum of the concentrations from both salts, which is 0.3 mol/L + 0.0300 mol/L = 0.3300 mol/L.
- Hydrogen phosphate ions (HPO4^2-): The concentration of HPO4^2- will be the same as the concentration from KH2PO4, which is 0.3 mol/L.
- Phosphate ions (PO4^3-): The concentration of PO4^3- will be the same as the concentration from K2HPO4, which is 0.0150 mol/L.

Therefore, the resulting solution will contain potassium ions (K+) at a concentration of 0.3300 mol/L, hydrogen phosphate ions (HPO4^2-) at a concentration of 0.3 mol/L, and phosphate ions (PO4^3-) at a concentration of 0.0150 mol/L.