The correct option is A 2.4
Given, VBa(OH)2=VHCl=400 mL, [Ba(OH)2]=1200M, [HCl]=150M, VH2O=200 mL
Number of H+ ions from acid N1V1=400×150=8
Number of OH− ions from base N2V2=400×1200×2=4
here, N1V1>N2V2 so solution will be acidic in nature.
so, [H+]=N1V1−N2V2Total volume
[H+]=(8−4)400+400+200
[H+]=4×10−3
so, pH=−log [H+]=−log 4×10−3
pH=3−2 log 2=2.4