Answer:- pOH will increase.
Explanations:- Originally we have an ammonia solution and we know that ammonia is basic in nature. The pH of a basic solution is greater than 7.
pOH = 14 - pH
So, if the pH is greater than 7 then the pOH will be less than 7.
Ammonium chloride or better to say ammonium ion is a conjugate acid of ammonia. So, if we add ammonium chloride to aqueous ammonia solution then a buffer solution is formed. We know that an addition of acid decreases the pH of the solution. If the pH is decreased then pH will increase.
Hence, an addition of ammonium chloride will increase the pOH of the aqueous ammonia solution.