I am a Non reactive, non metal, with 8 Valence electrons. What element am I?

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)

How many moles are contained in 5.6 l of h2 at stp

True or false exosphere is the least dense