Evaluation Methods. Several studies from around the world that have evaluated Incredible Years components meet the Promising Practices Network (PPN) criteria and have found Incredible Years to be a promising or proven program. These studies are listed below, by the component that was tested in the study.
The noble gases (arranged in order of increasing atomic weight) are helium, neon, argon, krypton, xenon and radon. Helium, neon and argon are the three noble gases with the lowest atomic masses. Helium, Neon, Argon. Helium, neon, and argon are the three lightest members of the noble  gases. Hydrogen is the lightest of all elements. According to the Periodic  Table, its atomic weight is 1.00794 u, even lighter than helium.
1 Hydrogen is the simplest element in the universe. 2  It is made up of one proton and one electron. 3  Hydrogen is the lightest of all elements and gases, and is 14 times lighter than air. 4  A gaseous hydrogen spill diffuses immediately into the air, and does not pollute the ground or groundwater. It is made up of one proton and one electron. 2  Hydrogen is the lightest of all elements and gases, and is 14 times lighter than air. 3  A gaseous hydrogen spill diffuses immediately into the air, and does not pollute the ground or groundwater. 4  Hydrogen is colorless, odorless and nontoxic.