Is #H_2S# an organic or inorganic gas?
The gas doesn't contain any carbon, meaning it can't be organic. All organic molecules contain carbon, most contain hydrogen and many contain oxygen.
Organic compounds are those that contain carbon-hydrogen bonds, i.e. we can say that all organic compounds are made up of carbon and hydrogen, as well as other elements if the molecule contains them.
That leaves hydrogen sulfide gas as an inorganic compound.
I hope this helps!