Some of them are. None of it is. None of them are. Most of the work is mine. Most of the apples are rotten.
Some nouns can name a group acting as one unit or refer to individuals within that group.
My family was happy to be at the reunion. My family were arguing about their plans. When the subject is plural, the verb must be plural. My sister and her husband are visiting me this week. Reading and writing are the core of education.