a$)$ Water with the ionic characteristics shown in the meq$/$L bar graph below is to be softened via chemical precipitation. Would you use the excess lime or the selective calcium process?

Briefly explain$/$support your recommendation. $[4$ marks$]$

b$)$ For excess lime softening, briefly explain what the purpose of recarbonation is in the first stage and the second stage of treatment. $[2$ marks$]$

c$)$ When using split treatment to soften a water, why is recarbonation not used after the first stage of excess lime addition? $[2$ marks$]$