Question

which of the following nitrates does not involve a reddish brown gas on heating:
(A) KNO3
(B) Cu(NO3)2
(C)Pb(NO3)2
(D) Ca(NO3)2​

Answer 1

Pb(NO3)2 will give a yellowish color

Answer 2

KNO3

Here reddish brown gas means NO2
And there is only KNO3 here which will not liberate NO2