Explain a project you have worked on in detail. What challenges did you face, and how did you solve them?” – This is often the one key question where interviewers gauge your real-world application, problem-solving, and communication skills. “What is polymorphism and how have you used it in your project?” – A favorite for checking object-oriented programming understanding. “Write a program to reverse a string / check for palindrome / Fibonacci series.” – Classic DSA entry-level filter questions.