They start you off with a written "quiz" with some basic chemistry questions, and one pretty basic critical thinking question. Then have groups of 5-6 employees ask you basic interview questions (not people actually trained to interview). There's 3 rounds or so of this, then you meet with actual HR staff at some point.

Two panels of three interviewed me. Each with chemists from different departments and an HR team member. The receptionist started me with a quiz to take that was fairly easy and about some basic chemistry questions and other conceptual questions.