Choose two justification statements (between a-d) that are relevant and appropriate for the conclusion written below.

Module II 4 Objective: To explain the difference in pH between the two salts: Na2CO3 and NH4Cl - Results: The pH determined by pH electrode is 10.75 for 0.10MNa2CO3 and 5.63 for 0.10 MNH4Cl solutions - Justifications in Discussion (Choose TWO from the following possible justification statements): (a) Na2CO3 solution absorbs CO2 gas from air, leading to a basic pH. (b) Na2CO32Na++CO32,Na2CO3 is a salt with 100% dissociation to Na+and CO32. CO32 is a weak base that partially reacts with H2O to release OHaccordingtothe reactions of CO32+H2OHCO3++OH and HCO3+H2OH2CO3+OH. (c) Na2CO3 reacts with HCl to form salt and carbonic acid (H2CO3) that decomposes to H2O and CO2:Na2CO3+2HCl=2NaCl+H2O+CO2 (d) NH4ClNH4++Cl,NH4Cl is a salt that completely dissociates to NH4+and ClNH4+is a weak acid that partially dissociates to NH3 and H+according to the reaction of NH4+ H++NH3 (e) NH4Cl solution is basic and absorbs CO2 gas from air, leading to an acidic pH. (f) All salt solutions containing sodium have a basic pH. Conclusions: The basic pH of Na2CO3 solution results from the weak base of CO32, and the acidic pH of NH4Cl solution results from the weak acid of NH4