Final answer:
In Bach's church cantatas, movements for soloists were generally arias, which are elaborate solo pieces with orchestral accompaniment designed for vocal expression.
Step-by-step explanation:
In Johann Sebastian Bach's church cantatas, movements for soloists were generally arias. An aria is a self-contained piece for one voice, usually with orchestral accompaniment, which features more elaborate melodic expression and is often seen as an opportunity for emotional expression and vocal virtuosity within the context of the cantata.
On the other hand, recitatives are a narrative style of singing that is more speech-like, whereas chorales are hymn tunes sung by the choir, often with the congregation, and fugues are a type of contrapuntal composition where a theme or subject is introduced by one part and successively taken up by others and developed by interweaving the parts.