Answer: pOH = 3.13
Ba(OH)2 is a very basic substance. The general formula for pOH is - log(OH)
Barium Hydroxide produces 2 moles of OH for every mole of Ba(OH)2 present in the solution.
0.00037 M = 3.7 * 10^-4 Ba(OH)2 will produce 2 *0.00037 M of OH-
OH- = 2* 0.00037 = 0.00074
pOH = - log(0.00074) = 3.13