Don’t say you became a chemist because it’s a lucrative field. Interviewers also use this question to determine your level of excitement. If there’s only one position and many qualified applicants, interviewers want to select someone who brings a lot to the table — knowledge, experience, a willingness to learn, and genuine excitement for the field. A good answer might include, “Since I was young I had an interest in learning more about properties and various forms of matter, and understanding how these undergo change.”