On heating Pb(NO3)2 a brown gas is evolved which undergoes dimerisation on cooling. Which is that gas Share with your friends Share 4 Akanksha C. answered this Dear Student, Regards 18 View Full Answer Suraj Gupta answered this The gas is no2 -5 Aniket Arya answered this NO2 -5 Devin B Thomas answered this The gas so evolved is NO2 which dimerises to give N2O4 5 Anugrah Johnson answered this Pb(NO3)2 --->PbO2+2NO2 NO2 gas is released when lead nitrate is heated which is brown in colour. GOOD LUCK>>> <<<CHEERS 1