To find the pOH of a solution, you need to know the concentration of hydroxide ions (OH-) in the solution. In the case of a strong acid like HCl, it completely dissociates in water, producing H+ ions and no OH- ions. Therefore, the concentration of OH- in a solution of HCl is effectively zero.
In this scenario, you can assume that the solution is neutral, and the pOH of a neutral solution is 7. So, the pOH of a 0.0235 M HCl solution would be 7.