"Is there any reason why you wouldn't hire me for this job?" This is a hard question to ask--but it's the only way you're going to find out if they have any doubts about hiring you. Knowing what they are gives you a chance to address those doubts and hopefully clear them up. Job seekers who ask this question increase their chances of getting hired by 30 percent.
"What are the biggest challenges of this job?" This question lets you know what the most important tasks are for this job, or what potential pitfalls may be waiting for you. It's also the perfect opportunity to show the hiring manager how, when faced with tough times, you turn to your inner strength and innate skills to find solutions.