What is a collective noun?
A collective noun is a noun that can be singular in form whilst referring to a group of people or things. Collective nouns are sometimes confused with mass nouns.
Groups of people - army, audience, band, choir, class, committee, crew, family, gang, jury, orchestra, police, staff, team, trio
Groups of animals - colony, flock, herd, pack, pod, school, swarm
Groups of things - bunch, bundle, clump, pair, set, stack
The use of "of"
We often say a group of things, such as a bunch of flowers, or a host of golden daffodils.
Some collective nouns can stand alone, such as "Britain has an army", but if the collective noun "army" is used to mean something other than an organized military force, you can say things like "an army of women" or "an army of ants", and even "an army of one".
Plural or singular?
When a group is considered as a single unit, the collective noun is used with a singular verb and singular pronoun.
For example - The committee has reached its decision.
When the focus is on the individual parts of the group, British English sometimes uses a plural verb and plural pronouns.
For example - "The committee have been arguing all morning." This is the same as saying "The people in the committe have been ...."
However, if you are talking about more than one committee, then you use the plural form.
For example - "Many committees have been formed over the years."
A determiner in front of a singular collective noun is always singular: this committee , never these committee (but of course when the collective noun is pluralized, it takes a plural determiner: these committees ).