You should never ask or be asked these questions during a job interview. It's actually illegal.
1. Have you ever been arrested?
It's not illegal to ask a candidate if they've ever been convicted of a crime, a candidate can not be asked about their arrest record.
2. Do you drink socially?
This is an odd question to ask in an interview, but it's considered illegal because of the Americans with Disabilities Act of 1990, which protects recovering alcoholics from having to reveal this information about themselves in a professional setting.
3. Do you observe any religious holidays?
Religion is a protected class, so it is illegal for recruiters to ask about it.
4. What country are you from?
This question is illegal because nationality discrimination is illegal. The only thing a potential employer needs to know is if you can legally work in this country.
5. Are you married?
Any questions pertaining to your marital status, children or plans to wed or have children falls under pregnancy discrimination. This is also a subtle way recruiters may try to ask about someone's sexual orientation. Job candidates are not required to disclose any of this information.
6. How old are you?
If a recruiter is asking in order to determine if a candidate is over 18, a requirement at many companies, this is fine. However, when asking older candidates this question, they may be discriminating based on age.
7. When did you graduate?
This is a subtle way of trying to figure out your age.
8. How's your health?
For physically demanding jobs, recruiters may ask about specific abilities that pertain to job duties such as "Can you lift 30 pounds on a consistent basis?" or "are you about to work a four hour shift on your feet with no break?" You're not required to reveal any other information about your health.
from lifehacker.com
“Have You Ever Used Drugs In the Past?”
This is another example of a loaded question that can mean a lot of things. First off, “drugs” can mean anything from illegal narcotics to prescription drugs, so it’s not clear to begin with. Secondly, ADA Policy Director Chris Kuczynski explains that an employer can’t ask about your past use unless it was perhaps tied into a crime you were convicted of (forcing you to mention it). And even then, it’s a sketchy subject to bring up without a good reason.
What they can ask you is if you are using any illegal drugs currently. You may even have to take a drug test at some point, so if you are, it may not matter how you answer this question. Just remember, your past is not information you usually have to disclose unless you’re interviewing for a government job or a job that requires some kind of thorough background check.
How to React to Illegal Questions and Discrimination
If you do encounter illegal questions like these it can be a bit awkward. If the question doesn’t seem to have any malicious intent, Michelle Cash at Experience suggests you try to determine what information they’re really after:
For example, if an interviewer asks if you have children, you may deduce that she wants to know if you’d be missing work often to care for them. You might simply answer that you have no problem meeting the position’s attendance requirements.
They may just not be very good at interviews, or maybe they’re new to it entirely. Try to give them what they want without giving up the information you know is yours to keep.
If it does feel like they are being discriminatory, however, or if you think you were denied a job because you refused to answer an illegal question, check with the U.S. Equal Employment Opportunity Commission. There you can file a charge of employment discrimination and learn more about the laws that protect you while you continue your job search. Don’t let your interviews turn into a horror story if you can help it, and always go in prepared and knowing your rights.