Answer:
1. To Entertain
The speaker was referring a joke which means that the purpose here was to entertain.
2. To Inform
The purpose of this is to inform the reader of the situation in the city with regards to a flood that was so significant that even cars could not pass.
3. To Inform
The purpose of this is also to inform as it aims to explain to the reader what the water cycle's main stages are.
4. To Entertain
The speaker here is trying to paint a picture of boys dancing a particular dance in order for the reader to imagine the scene and be happy.
5. To Persuade
This is an ad slogan by M&Ms and they are trying to convince customers to take M&Ms by talking about how nice the chocolate is such that it melts in a person's mouth.