Observe the below flow chart and pick out the suitable substances for X, Y and Z  respectively

i) NaCl, HCl, NaOH 
ii) ${\mathrm{Na}}_2{\mathrm{SO}}_4,{\mathrm{H}}_2{\mathrm{SO}}_4,\mathrm{NaOH}$
iii) HCl, KCl, KOH 
iv) ${\mathrm{Na}}_2{\mathrm{CO}}_3,{\mathrm{H}}_2{\mathrm{SO}}_4,\mathrm{NaOH}$
The correct combination is/ are