Which of the following elements is a polyatomic molecule?

Appeared in: RRB Nsg. Superintendent-20 July 2019 (Shift-1)

Explanation

Sulphur is classified as a polyatomic element, which means its stable molecules are composed of more than two atoms.
The most common and stable allotrope of sulphur at room temperature is orthorhombic sulphur, which consists of puckered, crown-shaped rings of eight sulphur atoms.
Therefore, its chemical formula is S₈, fitting the definition of a polyatomic molecule.

Option A: Chlorine is a diatomic molecule, not polyatomic. It naturally exists as two atoms covalently bonded together.
Option C: Argon is a monoatomic element. As a noble gas, it is chemically inert and stable as a single atom.
Option D: Nitrogen is a diatomic molecule. It forms a stable molecule with two nitrogen atoms joined by a triple bond.

Visual 1: Diagram - A 3D model of the S₈ crown-shaped ring structure to visually represent its polyatomic nature.
Visual 2: Diagram - Simple models of Cl₂, N₂, and Ar to contrast diatomic and monoatomic structures with the polyatomic S₈ molecule.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Atomicity of Elements as background academic context rather than a clinical decision trigger.
Understanding basic chemistry concepts like molecular structure is a fundamental prerequisite for grasping more complex topics in nursing, such as pharmacology, physiology, and biochemistry.
For instance, the properties of elemental sulphur (S₈) are very different from the sulphur compounds used in medications (e.g., sulfonamides). This distinction is rooted in chemical bonding and molecular structure.
What if the question asked about Phosphorus? Phosphorus is also a polyatomic element, commonly existing as a P₄ tetrahedron. This shows that other non-metal elements can also form polyatomic molecules.

How to Approach the Question

First, define the key term in the question: 'polyatomic molecule'. 'Poly-' means 'many', so this refers to a molecule containing more than two atoms.
Next, recall or deduce the natural molecular state of each element listed in the options.
Analyze Chlorine: It is a halogen, and halogens typically exist as diatomic molecules (Cl₂).
Analyze Sulphur: Recall that its most common elemental form is a ring of eight atoms (S₈). This fits the definition of polyatomic.
Analyze Argon: It is a noble gas. Noble gases are known to be chemically inert and stable as single atoms (monoatomic, Ar).
Analyze Nitrogen: It is a common gas that exists as a diatomic molecule with a strong triple bond (N₂).

Concept Tested & Keywords

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Practise the full RRB Nsg. Superintendent-20 July 2019 (Shift-1)

Attempt every question from this paper in a timed mock, then review the full solution for each one.