1 M NH4OH and 1 M HCI are mixed to make total volume of 300 mL. If pH of the mixture is 9.26 and pKa(NH4+) = 9.26 then volume ratio of NH4OH and HCl will be

pH = 9.26 indicates [NH4OH] > [HCl] and thus, mixture is a buffer since, HCI will react with equivalent amount of NH4OH forming NH4Cl.Let HCI = x mL x millimolesNH4OH=(300−x)mL=(300−x) millimoles  NH4Cl formed =x millimoles  NH4OH unreacted =300−x−x=(300−2x) millimoles  pOH=14−9.26=4.74 pKb=14−9.26=4.74 pOH=pKb+log⁡NH4+NH4OH 4.74=4.74+log⁡x(300−2x) x300−2x=1 ∴ x=100mL= volume of HCl (300−x)=200mL= volume of NH4OH hence, 2:1