An employer may ask a range of questions during a job interview.
The porpuse of the questions is to find out if a certain candidate may suite to a position.

As an employer, make sure you define the job requirements and the type of employee you are looking for – both skills competencies and behavioral qualities.

One may be interested to find out a balanced person that will win over other candidates because of his personal abilities, good background and his motivational skill.

This article suggests sample interview questions for employers to ask a candidate.
After reading this article, you may be interested in reading:
Candidate’s selection criteria, How to interview a candidate?
The job interview process 

Employer questions to ask in an interview – the Interviewer job interview questions

Here are many good interview questions for employers. Please select the interviewing questions according to your needs:
General questions – introduction
• Tell me about yourself
• Where have you worked before?
• What is your current position in the company?
• In your previous job, what was your exact profile?
• What are some of the projects that you handled in the previous job?
• Where have you got your academic qualifications from?

Some tough and frequently asked questions
• Why should we hire you?
• Why do you want this job?
• Why were you fired?
• Why do you want to work for this company? Why do you want to work here?
• What are you weaknesses & strengths?
• Why did you leave your last job? What are the reasons you left your last job?
• What (value) do you bring to the company? – Your qualifications for the job requirements.
• Why do you think you would make a great addition to our team?
• How long will you work for us?
• How is your relationship with co-workers? What do colleges or supervisors say about you?
• Give us examples of situations of pressure that you faced.
• Give an example when you have worked out above/beyond your normal job profile to make something happen for the company.
Refer to the tough and frequently asked questions category for more details.

Career questions
• Why did you choose this career? How did you decide to choose this career?
• What do you want to do 5 years from now?
• Where do you see yourself ten years from now?
• What are your long and short term career goals?
• What are your career objectives? What’s your career path planning?
• If not this career, which other career would you have taken?
• Provide additional information regarding courses/programs/lessons that you took.
• Do you enjoy work?
 
Other general questions
• What do you know about this company?
• When can you join us? Your availability
• What are your hobbies and likes and dislikes?
• Do you have any questions to ask us?

Salary questions
• What are your salary expectations?
• What is your current salary?
• What are your financial expectations from any job in your life?
• Are you happy with your salary so far?
• What salary do you need or look for?

Many questions for interviewers to ask a professional candidate can be found in:
Management job interview category – many interview questions for managers.
Teaching job interview category – questions for teachers.
Professional job interview - interview questions for some major professions.