A solution with PH 12 has a poh of ____ and hydronium concentration of ____

The relationship between pH and pOH at $25^\circ\text{C}$ is given by:

$$\text{pH} + \text{pOH} = 14$$

Given $\text{pH} = 12$:

$$\text{pOH} = 14 - \text{pH}$$ $$\text{pOH} = 14 - 12$$ $$\text{pOH} = 2$$

The hydronium concentration can be calculated from the pH using the formula:

$$[\text{H}_3\text{O}^+] = 10^{-\text{pH}}$$

Given $\text{pH} = 12$:

$$[\text{H}_3\text{O}^+] = 10^{-12} \text{ M}$$

A solution with PH 12 has a pOH of $\boxed{2}$ and hydronium concentration of $\boxed{10^{-12} \text{ M}}$.