10 core electrons are in argon.
Water , H2O, is a molecule made of oxygen and hydrogen. The bonds that hold water molecules together are due to shared ELECTRONS, and known as covalent bonds
The ocean is more dense than a freshwater lake.
Noble Gases is the answer. These elements have a full outer shell composed of eight valence electrons, meaning that they do not need to gain electrons from other elements in reactions, making them nonreactive (inert).