You may be contacted for an interview as part of your application. Whether this happens or not depends on the school you apply to, and there are plenty of reasons you may or may not get an interview regardless of the final decision. Do not stress if you do not get contacted.
The exact questions will vary, but here are some basic ones you should be prepared for:
- Why do you want to do research? Why not pick an industry job?
- Why do you want to go to [the school you’re applying to] specifically?
- What exactly were your contributions for [project you mentioned in your application]? What is its overall goal? (It’s really important to be able to answer this one concisely and accurately; interviewers want to gauge if you actually know what you’re talking about, or if you just did small things related to the project but don’t have a high-level picture)