Answer:
1) When lead nitrate is heated in a test tube, lead oxide, nitrogen dioxide and oxygen are formed. During heating of lead nitrate, we see two colours that is yellow and yellowish brown. Yellow colour represents the formation of lead oxide while yellowish brown colour indicates the formation of nitrogen dioxide.
2) The name of this reaction is thermal decomposition.
3)The chemical equation is as follows:
2Pb(NO3)2 - - - -2PbO + 4NO2 + O2