Hung frozen in the air like a hunk of smoke. what type of figurative language is this?

Simile

Explanation:

Similes compare two unlike things USING like or as. In this case, it is using like. This is different from a metaphor which compares two unlike things NOT using like or as.

quite an interesting way to teach topic sentences, because the answer to this question is the best definition of a topic sentence that one can present, it is as if answering the questions taught you how to do it, this is some real teaching, it is terribly well-done.

the topic sentence in this paragraph is:

topic sentences writers stay on track and keep a paragraph from becoming an aimless collection of sentences about an idea.

which incidentally tells you what a topic sentence should be.