1. Difference between PriorityQueue and Dequeue. 2. Difference between ArrayList and LinkedList. 3. Difference between Hashtable and Hashmap. 4. Can a Hashtable have NULL values? 5. 25 Horses puzzle (Google it and you'll find details.) 6. Explain your exact role in current project and how you're doing automation. 7. SQL Joins. 8. Selenium advanced concepts plus Framework Designing.