Final answer:
A 1 M solution of KNH2 would have the lowest pOH because NH2- is the strongest base among the compounds listed, leading to the highest concentration of OH- ions.
Step-by-step explanation:
To determine which 1 M solution has the lowest pOH, we need to identify the compound that acts as the strongest base. pOH is a measure of the hydroxide ion concentration in solution, and the stronger the base, the higher the hydroxide ion concentration, resulting in a lower pOH value.
Among the given compounds, KNH2 contains the anion NH2-, which is the conjugate base of the weak acid NH3. This makes it the strongest base. Therefore, a 1 M solution of KNH2 would have the highest concentration of OH- ions and thus the lowest pOH.