We use apostrophe +s (‘s) to talk about things associated with one person:
My friend’s name is Natalia.
These are my husband’s things.
We uses s + apostrophe (s’) to talk about things associated with more than one person:
Here is my sisters’friend.
The students’records are in the cupboard.
Note that we use an apostrophe + s (‘s) with irregular plural nouns:
The children’s party is at the club.
We also use apostrophe +s (‘s) on it’s own:
My birthday is the same day as my mother’s.
We use of to talk about things associated with places and objects:
Madrid is the capital of Spain. (not Spain’s capital)
The answers are at the back of the book.