Answer: Noble gases.
- A Noble gases
- B Halogens
- C Alkali metals
- D Alkaline earth metals
Correct answer: A. Noble gases
Explanation: Group 18 elements are noble (inert) gases; they have complete valence shells.
The complete modern periodic table (118 elements). Image: Cepheus et al., Public Domain, via Wikimedia Commons.
Concept context
The periodic table organises all 118 elements by atomic number and similar properties. Study periodic trends like atomic radius, ionization energy, and electronegativity, and learn how an element's position predicts its behaviour.
Read the full Classification of Elements and Periodicity in Properties notes →