Question: what is the empirical formula for beta-carotene?
Answer: Not until 1907 was the empirical formula of beta-carotene, C40H56, established by Willstatter and Mieg. The structure was elucidated by Karrer in 1930-31. This was the first time that the structure of any vitamin or provitamin had been established, and he received a Nobel prize for his work.