W. R. Grace & Co. R D Chemist interview questions

Applied in April, received an interview schedule beginning of June. Interviewed with 6 people for three hours, had a mixed feeling, but mostly positive, because of need to tune-in with a different person every half a hour. I felt pretty relaxed, because I was well-prepared answering interview questions about my career. In the end of three hour interview tour I was offered to share lunch with a hiring manager and several colleges. Even I tried to behave relaxed, by this time I was really exhausted, and I am not sure i made the right decision to go for lunch. I tried to show myself from the best side, and felt this way during an interview, however I was not offered a position unfortunately.