Generally, Selenium Interview questions would be on the fundamentals of the Selenium framework and how it is practically used to automate various web UI components from the browser.
Below are some of the selenium related questions that can help you prepare for the Interview:-
What is Selenium and why do we use? Any alternatives?
What are the differences between Selenium IDE, Selenium RC, Selenium1.0, Selenium2.0, WebDriver?
What Selenium versions and drivers you had used?
How do you develop automated tests for a given web site? Explain end-to-end process flow?
Can you briefly explain on how to write a simple Selenium test?
What are the different web elements that you can find from Selenium and the list of actions performed?
How does the page loading happen in WebDriver? How long does the test code to wait?
What are different WebElement locators? How do you find those elements? What tools or strategies do you use?
How to maximize the browser window?
How to switch between windows and frames?
What are the challenges that you faced with Selenium automation?
How do you test Ajax requests?
What is implicit and explicit wait?
If you want to make your career in Selenium testing then you must take up the following Selenium training Course. If you are interested in reading the stuff then you must read the following Selenium Tutorial. I am mentioning a video tutorial for you to understand the basics of it..