Anyone fast replyers?

How many atoms or molecules are there in a mole of a substance?

If 10.5 l of a at 0.98to 1.50 , is ?

An engineer decides to use a slightly weaker material rather than a stronger material, since she knows that the stronger material can break suddenly. this is an example of what? a choosing a material that will show warning before it fails b using composite materials that combine strength c using a material for multiple applications d using design techniques that increase efficiency and reduce cost