Which of the following is incorrect?
A. `wedge_m ^@ NaCl - wedge_m ^@ NaBr = wedge_m ^@ KCl - wedge_m^@ KBr`
B. `wedge_m ^@ H_2O = wedge_m ^@ HCl + wedge_m ^@ NaOH - wedge_m^@ NaCl`
C. `wedge_m ^@ NaI - wedge_m ^@ NaBr = wedge_m ^@ NaBr - wedge_m^@ KBr`
D. `wedge_m ^@ NaCl - wedge_m ^@ KCl = wedge_m ^@ NaBr - wedge_m^@ KBr`