I had read a lot in glassdoor and other websites what they usually ask. But I forgot the simplest question to think well about, and that was why I like the specific field of chemistry that I have studied and I want to work in that area. It is a simple question, but believe me, if you never thought about it, in some words that will convince public and scientists, it will be challenging to answer. The second thing I did not expect, and also not read in the interview-reports that I studied so far, was the end part of the interview when they asked me I can ask my questions if I have. I could ask a better and more intelligent question if I had thought about it.