A question asked in order to expose ignorance

Teachers sometimes refer to this kind of question as a trap:

From The Pragmatics of Mathematics Education by Tim Rowland:

One common perception is that the questions teachers ask their pupils are not searchlights focused to reveal truth, but traps set to expose ignorance.

Rowland was quoted in Teacher-student Interaction by Alandeom Wanderlei de Oliveira.

Seymour B. Sarason expresses the same notion in a different way in Letters to a Serious Education President:

They are both surprised and puzzled by my question, as if I am setting a trap to expose their ignorance.

If you are trying to educate, instead of expose, the answerer, I would say Socratic.

Teachers and politicians sometimes call these "gotcha questions."

Here's an excerpt from a discussion of gotcha questions in a Daily Caller article:

The infamous “gotcha” question is something politicians always rail >against. But what exactly defines a “gotcha”?

“I suppose a gotcha question is one that’s fundamentally unfair because it has a hidden or misleading premise,” former Clinton White House adviser and CNN contributor Paul Begala told The Daily Caller. He provided this example: “Q: Which Yankee before Jeter had 3,000 hits? A: No one!”

“A gotcha question is a knowledge question in which the moderator attempts to make the person … look stupid,” offered infamous Republican political consultant Roger Stone. “I think it is more like saying to Donald Trump, you know: ‘How many members of the U.S. House of Representatives [are there]?’”