Noble Gases and Their Applications

The periodic table is organised into groups (vertical columns) and periods (horizontal rows).

Noble gases sit at the far right of the periodic table in Group 18, sometimes also called Group 0 or Group VIII.

He, Ne, Ar, Kr, Xe, and Rn all belong to Group 18. The correct answer is Group 18.

Group 1 contains the alkali metals such as lithium and sodium — these are highly reactive, the opposite of noble gases.

Group 17 contains the halogens (e.g., fluorine, chlorine), which are also highly reactive.

Group 16 contains chalcogens like oxygen and sulfur, which readily form compounds.

Only Group 18 contains the unreactive noble gases at the far right of the periodic table.

The first shell holds up to 2 electrons, the second holds up to 8, and the third holds up to 8 (for the first 18 elements).

Argon has 18 electrons. First shell: 2, second shell: 8, third shell: 8. Total: 2 + 8 + 8 = 18. ✓

The outer shell has 8 electrons — a complete shell, confirming argon's chemical inertness.

2 + 8 + 6 = 16 electrons, not 18. This matches sulfur (atomic number 16), not argon.

2 + 8 + 18 = 28 electrons, which is far too many for argon (atomic number 18).

2 + 8 + 10 = 20 electrons. This does not match argon's atomic number.

2 + 8 + 8 = 18 electrons. This is correct for argon and shows a full outer shell of 8 electrons.