Preparing for a job interview is a task few enjoy. Articles abound on how to ace a job interview, but there's little guidance out there on how an employer can ace these interviews too.

I can tell you first-hand: Hiring someone is one of the most difficult decisions you will have to make simply because it has the potential to drastically impact your whole team and indeed your business. As a startup, each person you bring on can change the whole dynamic of the company.

A lot rides on the handful of interviews that you have with a potential employee. Assessing a candidate's skill-set, work ethic, and personality in one or two meetings is a tall order.

That's why I love the job interview questions asked by the CEOs below. Collectively, they've employed thousands of people in their lifetimes and have come up with certain questions that "cut to the chase." Some opted for trick questions (see No. 5); others present potentially challenging situations to test people's reactions (check out No. 12).

Here's some of the must-ask interview questions that these leaders ask potential employees:

  1. Tell me about your last job? is legendary CEO Jack Welch's No. 1 interview question. Criticizing your former employer is a big no-no, he says. "I want somebody who, when you're interviewing them, is frustrated by the lack of opportunity. They liked what they were doing, they liked their associates. They thought the company was good. But it just wasn't big enough for them."
  2. Why would you like to work for us? asks Francesco Venturini. This question can solicit a variety of answers, but the CEO of Enel X, an Italian energy company, wants to uncover what truly incentivizes a job candidate. "It's extremely important to understand what's motivating them," he says.
  3. Where do you want to be in a certain amount of time? There is no right or wrong answer to this question, assures the founder and CEO of Poshmark, Manish Chandra. But it gets to the heart of an individual's specific expectations. "It shows me sort of what their passion is or what they really think of themselves or what their aspirations and goals are," says Manish.
  4. Is this position right for you? By asking this question, Geoff Ramsey likes to turn the interview tables around to the potential employee. The co-founder of e-Marketer has discovered that this particular question truly tests the mettle of candidates. "Sometimes they end up looking blankly and saying 'I really don't know,' and then we both maybe discover that this isn't the right position for them. And sometimes a light goes on and they say 'Oh my gosh, this is why this job and this company is right for me!' and that passion, that energy that comes out when they answer that question."
  5. How much money does your local movie theater make? asks Olga Vidisheva, founder and CEO of Shoptiques. Olga asks this highly technical question regardless of the job title because she wants to discover how a potential candidate thinks. "I want to avoid people who overthink things, and you start seeing that, because in a startup, overthinking is bad. So you have to be able to be decisive. You have to be able to actually be logical and strategic in your answer. So that gets me a lot of kind of insights around the person," she says.
  6. If you were to walk on stage, what theme song would be playing? is Nick Taranto's must-ask job interview question. The Plated co-founder admits that it throws people off, but this is a valuable approach, as "you see how they react to something non-traditional."
  7. What is their dream for themselves? Mellody Hobson finds that this question truly reveals an interviewee's motives. The president of Ariel Investments recalls an interview in which a candidate said his dream was to own a Christmas Tree farm. To which Mellody replied: "'Why are you sitting in an investment firm?' Then they give you an answer about the money, and then you know that's not the right person for you."
  8. What would the person closest to you say is your best trait? Kat Cole asks this question as a playful way for candidates to describe themselves. "You get to a lot of truth," says the group president of FOCUS Brands, and it "allows me to probe a little further in[to the candidate's] style and characteristics."
  9. What are you going to do the same and what are you going to do differently than your predecessor? is a question that Honeywell executive chairman David Cote typically asks candidates. For David, the correct answer to this question is a delicate balance between respecting the work that has been accomplished and the wish to build upon it. "The culture I dislike is where whoever goes in new into a job has to tear down everything that the previous guy did. I always thought that makes no sense. I'm trying to build something here, not trying to tear something down. By the same token, a company always has to evolve, and that's a big theme within our company is that idea of evolution," says David.
  10. What's one thing you would do differently in life and why? asks Mitch Roschelle, partner and business development leader at PwC. This question typically sparks self-reflection and analysis in the recipient, which is exactly what Mitch is looking for.
  11. What are your weaknesses? is Susan Lyne's must-ask job interview question. It's a notoriously difficult question to answer, but the president and founding partner of BBG Ventures finds it draws out interesting responses from a candidate.
  12. How would you find a needle in a haystack? is a "left-of-field" but effective question asked by founder Scott Kurnit. He describes a telling response to this question that he encountered: "I had somebody say, 'Well, I would hire a consultant.' Well, I almost ended the interview there, because in a young company, the last thing we need is consultants--we need it inside the company."
  13. Tell me about yourself? Gary Vaynerchuk, CEO and co-founder of Vaynermedia, asks this because "I don't have like a jab to set up, the right hook in interviews." A disbeliever in current recruitment practices, Gary advocates the following approach to hiring: "My whole game is like, 'I don't know. As long as there's nothing that's clearly wrong, or my vibes don't feel bad, you're hired.' I'm optimistic. And then if I'm wrong, we will fire you. I don't know, it's not that crazy."
  14. What were you like in high school? Chairman and CEO of Alleycorp Kevin Ryan's go-to interview question delves into the candidate's younger psyche. For many interviewees, teenage years were a period when they had the time to really pursue their passions. By asking this particular question, Kevin hopes to glean a greater understanding. "I just want to get to know this person and understand who they are and a little bit about how they're going to fit in," he says.
  15. If I talked to five people in your office hallway about you, give me three things that they would say? This is Oath CEO Tim Armstrong's favorite question. "What it does is it puts people in a mental zone where they start really thinking what those people would say and they can't help but say what those people would say about them." Tim describes some of the most revealing answers he has heard in response to this question, like, "I'm the most political person in the office" and "I don't like to work with other people."