Read the sentence. the exquisite old painting hanging slightly crooked over the mantelpiece commanded our attention. which part of the sentence is a prepositional phrase? exquisite old painting hanging slightly crooked over the mantelpiece commanded our attention

The prepositional phrase is over the mantelpiece.
A prepositional phrase obviously starts with a preposition and also includes words closely connected to that particular preposition. In the sentence above, there is only one preposition, and that is the word 'over.' Therefore, the prepositional phrase would be 'over the mantelpiece.' 

Where is the passage or did you forget to change it.