NH42Cr2O7 on heating liberates a gas. The same gas will be obtained by

On heating, (NH4​)2​Cr2​O7​ gives, nitrogen gas. (NH4​)2​Cr2​O7​ → N2 ​+ Cr2​O3​ + 4H2​O        (Orange)        (Green)                            But whenever, NH4​NO2​ and NH4​NO3​ heated, then nitrogen and nitrogen dioxide gas liberated.NH4​NO2​→N2​+2H2​ONH4​NO3​→N2​O+2H2​O