What question will they ask you at the interview to remove condition of your green card?

Most of the time, you will have no interview. If both spouses signed the petition and included supporting evidence that the marriage is still very much alive, there should not be any interview at all.

It really depends on what you have already submitted as part of your I-751 petition but the USCIS can ask similar questions to what was asked at your initial adjustment of status interview when you first got the green card. Basically, the questions will be about the bona fide nature of your marital relationship.

At the interview to remove conditions on your residency status, USCIS can pretty much ask any question they need to prove that you were married in good faith. In that regard, they will usually ask questions as to how your relationship was established, what has happened since your marriage, and what your intentions or plans are for the future. You will also be asked to submit documentation of your marriage too.