this is what i think.

1. How pretty the sun is- declarative
2. Don't stand so close to the edge- imparative
3. It was quite chilly at night-exclamatory
4. Look at us riding on mules in this canyon- exclamatory

I disagree with your answers for 1 and 3. Number 4 could be right, although I could make a strong case that it's wrong.

Declarative statements make a statement.

Exclamatory sentences show emotion.

http://www.kwiznet.com/p/takeQuiz.php?ChapterID=2293&CurriculumID=16