The roughly 200 collective nouns in the English language cause a lot of confusion, but there's a simple answer, writes grammar expert June Casagrande.

When both nouns joined by “or” are singular, the verb form is easy: It’s singular, as we saw in “Ned or Nancy is.” When both nouns joined by “or” are plural, the verb is plural ...

Many is normally plural, but it takes a singular verb when a singular noun follows the phrase “many a” as in the following examples: • Many a teacher has taken the eligibility test.