Question

The family of elements which is least reactive is:

• A. alkali metals
• B. alkaline earth metals
• C. noble gases
• D. halogens
• E. transition metals

Answer 1

Answer: (C)

noble gases

Due to full-filled orbitals, the noble gases are least reactive.
The properties of the noble gases can be well explained by modern theories of atomic structure: their outer shell of valence electrons is considered to be 'full', giving them little tendency to participate in chemical reactions, and it has been possible to prepare only a few hundred noble gas compounds. The melting and boiling points for a given noble gas are close together, differing by less than $10{}^{o}C$ ($18{}^{o}F$); that is, they are liquids over only a small temperature range.