Is it possible to major in a science subject (like Chemistry or Physics) and minor in a humanities or social science subject (like Journalism or International Relations)?

Yes, completely normal. The liberal arts model encourages interdisciplinary study where you’ll typically take 10-12 courses in your major, 5-6 in your minor, and the rest are general education/electives. For example, Yale allows Chemistry majors to minor in Global Affairs; Berkeley offers Physics with a Journalism minor easily.