How does an airbag protect a passenger in a car accident?

Good question. It like a fail safe,if you hit a car tail gate going slightly fast it come out to protect you from hitting your on the the wheel or the mirror. See if you don't have a seat belt or it just don't fully stop you the airbag might help.Like concussions.  I Hope This Help you :)

Alkaline earth metals are found in group 2 of the periodic table.