My family left the fair at 8:00, so we missed the fireworks display.
is this a Simple Sentence
Compound Sentence
Complex Sentence
Compound-Complex Sentence?

Hey there!

Compound

Explanation:

It contains a main clause (My family left the fair at 8:00) a conjunction(so) and another main clause (we missed the fireworks display).So it's a compound sentence.

-It can't be a simple sentence because it has a subordinate clause.

-It can't be a compound Complex sentence because it only has 1 main clause and not 2.

-It can't be a complex sentence since it doesn't have a subordinate clause.

Definitions:

A simple sentence has 1 main clause.e.g. The boys fought.

A compound sentence has two main clause E.g. Peter went to the mall and he returned late.

A compound conplex has 2 or more main clauses and 1 or more subordinate clause.E.g. Jude travelled and she brought her cousin to live with her.

A complex sentence has a main clause and a subordinate clause.E.g. The boy bumped into the table and he fell onto the floor.

Note:

A main clause is a group of words that can stand on its own whilst a subordinate clause can't as it doesn't represent a complete idea.

Hope this helps!

c. in order of atomic number