1) What is multithreading? 2) How do you create threads and how do you resolve thread issues? 3) How would you update an UI element when two threads are accessing it simultaneously? 4) How would you prevent two instances of an application from opening? 5) What is async programming and how to create task based method? 6) Out vs Ref? 7) What is Dependency injection? 8) Did you work between managed and unmanaged codes (C++ and C#)? 9) Which design patterns did you use? What is singleton? 10) What is background worker? 11) Do you have any question?