I want to say something like "the antibacterial activity of these three drugs is the same".
I am not sure whether i should use activity or activities in the above sentence, since three drugs are mentioned.
Learn English – Should I use activity or activities
grammaticality
Best Answer
This is a matter of preference. Activity is one of those odd nouns which is singular but can stand in for a plural. "We are tracking his activity" and "We are tracking his activities" are very close, but the latter implies tracking the individual granular components of his overall activity rather than his general status.
I would lean towards "activity" because you are trying to make a global statement about a property of the drugs rather than a low-level pinpoint analysis.
The sentence might trip up a reader either way, so I might suggest a rearrangement:
In fact, "activities" would be perfectly legal there too, but with the same implication. "Activities" makes the reader think of the individual strands and how they map up perfectly with one another, which is not important here.