One group of atoms on the periodic tables are known as "noble gases". why have they been given this name?

Standing side by side ,you and a friend step off a bridge at different times and fall for 1.6s to the water below.your friend goes first,and you follow after he has dropped a distance of 2.0m.when your friend hits the water,is the seperation between the two of you 2.0m or more than 2.0m? verify your answer with a calculation.

Asystematic approach to problem solving is called a (an)

Ihave a density of 1.61g/cm^3 and a mass of 28g. find the missing value