Which salt on heating does not give brown coloured gas ?

1) 4LiNO3→∆2Li2O+4NO2↑Brown gas+O2↑ 2) 2KNO3→∆2KNO2+O2↑ 3) 2PbNO32→∆2Pb2O+4NO2↑+O2↑ 4) 4AgNO3→∆2Ag2O+4NO2↑+O2In IA group nitrates only LiNO3 gives NO2[Brown gas] remaining IA group nitrates donot gives NO2 gas and they undergo decomposition in different manner