Question

which metal nitrate gives colourless gas on Thermal decomposition

Answer 1

I think this is the ri8 ans....
Ba (NO3)2

Answer 2

Ans : Ba(NO₃)₂ , barium nitrate

Actually, thermal decomposition of Ba(NO₃)₂ gives BaO , oxygen gas { colorless } and NO₂ gas ,. e.g.,
2Ba(NO₃)₂ --------> 2BaO + 4NO₂ + O₂ { colorless gas }