Which of the following does not participate in the Solvay process for the manufacture of Na2CO3?

2NH3 + H2O + CO2 → (NH4)2 CO3(NH4)2 CO3 + H2O + CO2 → 2NH4 CO3NH4HCO3 + NaCl → NH4Cl + NaHCO3↓ → Due to the low solubility of NaHCO3, it gets precipitated in the reaction of NaCl with NH4HCO3 the sodium bicarbonate on calcination gives thermally stable sodium carbonate.→ H2SO4 doesnot participate in the solvay's process.