Oxygen, sulphur, selenium, tellurium, polonium and livermorium constitute Group 16 of the periodic table. This is sometimes known as group of chalcogens. The name is derived from the Greek word for brass and points to the association of sulphur and its congeners with copper. Most copper minerals contain either oxygen or sulphur and frequently the other members of the group.

The elements of Group16 have six electrons in the outermost shell and have ns²np⁴ general electronic configuration.

Due to increase in the number of shells, atomic and ionic radii increase from top to bottom in the group. The size of oxygen atom is, however, exceptionally small.

Which of the following does not exist as an octatomic solid?

Oxygen

The correct answer is option 4. Oxygen.

The element that does not exist as an octatomic solid is Oxygen.

An octatomic solid refers to a solid structure composed of eight atoms of the same element bonded together. Sulfur \((S)\), selenium \((Se)\), and tellurium \((Te)\) are known to exist in octatomic solid forms. For example, sulfur can form \(S_8\) rings, selenium can form \(Se_8\) rings, and tellurium can form \(Te_8\) rings. However, oxygen \((O)\) does not typically form octatomic solid structures. Instead, oxygen is commonly found in its diatomic molecular form, \(O_2\), in the gas phase or as \(O_3\) (ozone) in the atmosphere. While it is possible to create higher allotropes of oxygen under extreme conditions, such as high pressure and temperature, they are not stable under standard conditions and are not commonly encountered as octatomic solids.