In American English, collective nouns (e.g. mob, jury, team, committee etc) always take a singular verb. In British English, collective nouns can be followed by both singular and plural verbs. Singular verbs are preferred when the speaker thinks of the group as a single whole. Plural verbs are preferred when the reference is to the individual members in the group.

Compare:

The mob has gathered quickly. (Here we use a singular verb because the reference is to the group and not to the individuals of which it is composed.)

The mob were scattered in all directions. (Here we use a plural verb because the reference is to the individual members of which the group is composed.)

The nouns means and pains take either the singular or the plural verb; but the construction must be consistent.

His means are small but his heart is generous. (Plural)

All possible means have been tried to restore peace. (Plural)

In the nineteenth century a new means of transport was developed.

Great pains have been taken to solve the problem.

None should be used in the singular but popular usage accepts the plural form as well.

None of his books are best sellers. (Plural)

‘Are there any pens in the box?’ ‘There are none.’ (Plural)

‘Was there any letter for me?’ ‘There was none for you.’