If anyone can help me with these 3 i will genuinely appreciate it sm. plz help a brother out

Which type of reaction always has an element and a compound as reactants

Observation and experimentation have led many scientists to accept a theory about the origin of the universe. this theory is called the big bang theory. scientific evidence collected and observed by scientists around the world suggests that the universe is ever expanding from a hot and dense initial state. what makes this a scientific theory? (2 points)

Which organism develops breathing organism develops breathing organs from pharyngeal arches? shark, spider, sea star, sea horse