单项选择题

已知H3PO4=2.12,=7.20,=12.36,0.10mol·dm-3Na2HPO4溶液的pH约为(    )
   A.4.7    B.7.3    C.10.1 D.9.8

A.174.24.96:6088/Latex/latex.action?latex=cEtfe2ExfV57XG9taW51cyB9'
B.12,C.174.24.96:6088/Latex/latex.action?latex=cEtfe2EyfV57XG9taW51cyB9'
D.20,E.174.24.96:6088/Latex/latex.action?latex=cEtfe2EzfV57XG9taW51cyB9'
F.36,0.10mol·dm-3Na2HPO4溶液的pH约为(
G.4.7
H.7.3
I.10.1