Why is the sodium ion, Na+1, smaller than the sodium atom?

Why does a plastic bottle that is sealed at a high altitude change it’s shape when taken to lower altitude

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)

Astudent uses universal ph paper to find the ph of three solutions . solution a has a ph of 5 solution b has a ph of 11 and solution c has a ph of 7 identify which solution is acidic which solution is neutral and which solution is basic