Reactivity, like most (if not all) words that end in "ivity", is a noun. It is a noun formed from the adjective "reactive". Other words ending in "ivity" include creativity, connectivity, activity, and sensitivity.
adverb
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Krypton's reactivity level is low to none at all, since it's part of the inert gases family.
part of speech
The part of speech for this particular word is a noun.
what part of speech is beneath
what part of speech is work
adverb
Sashay is a verb. It means to walk in an exaggerated, showy manner, often with hip swaying.
The word speech is a noun.
Adjective
Yes, conjunction is a part of speech.
What part of speech is thaw
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