For some odd reason I think we use the plural form of gas for that. "Det är bara gaser" :).
Perhaps it is because there are various chemical compounds in it, such as methane and carbondioxide. But I doubt that. I expect it would be an explanation after the fact.
Even weirder is that in Portuguese it's the exact same thing: (s.) gás - like any sort of gaseous substance; (pl.) gases - the plural of "gás" OR fart :D
No, Swedish borrowed it directly from the German Benzin, as did English.
Trying to think of a circumstance where you would say. "its only gas!". Haha only ironic ones spring to mind.
People sometimes say it when a baby smiles... it's only gas, meaning it's just an automatic reflex to internal rumblings, not a real expression of emotion.
If something is great fun in Ireland you can say "It's only gas (craic)"
One question, why is the t mute in det even in the slow version? Is it incorrect to pronounce it with the t added in the end?
I've honestly never heard gōs for gossip... guessing it's dialectal and/or very colloquial. Normally, skvaller is the right word for it.