gassing vs chemical action

gassing and chemical action both are nouns.

Word	Noun	Adjective	Verb	Adverb
gassing	Yes	No	No	No
chemical action	Yes	No	No	No

As nouns, chemical action is a hypernym of gassing; that is, chemical action is a word with a broader meaning than gassing:

gassing: the process of interacting with gas
chemical action: (chemistry) any process determined by the atomic and molecular composition and structure of the substances involved

Other hypernyms of gassing include chemical change, chemical process.

gassing (noun)	chemical action (noun)
the deliberate act of poisoning some person or animal with gas	(chemistry) any process determined by the atomic and molecular composition and structure of the substances involved
the process of interacting with gas