Describe what a voltaic cell is and how it works, then explain how the voltage of the cell is determined. compare and contrast this type of cell with a fuel cell. (electrochemical cells)

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)