At 298 K, the pH of mixture containing 1000 ml of 0.1 M H2SO4 and 500 ml of 1.2 M NH4OH is (pkb of NH4OH = 4.77)

VaNa=10000.12=200 meqVbNb=5001.2=600 meqSA     +           WB        →          salt   +   water200 meq      200 meq            200 meqLeft over WB= 600-200 meq =400 meq ;This mixture contains WB and its salt of strong acid.This mixture acts like a basic buffer.∴pOH=pKb+logVSNSVaNa    pOH=4.77+log200400    pOH=4.77−0.301      pH=14−4.77+0.301      pH=9.531