How does mozart serenade eine kleine nachtmusik fit the model for multi movement instrumental works in this era?

The answer is string quartet and double bass, with frequent modulations, wanders trough series of foreign keys.

Explanation:

The serenade is a four movement piece with a string quartet and double bass. It is from the Classical Era and the first movement is in sonata-allegro form. The opening of the first movement of Eine Kleine Nachtmusik begins with a marchlike theme that rapidly ascends to its peak, a rocket theme, them turns downward at the same rate.

The overall form of the third movement of the serenade is ABA, with frequent modulations, wanders trough series of foreign keys.