Question

Which one of the following molecule exists as tetra-atomic molecule?

• A. Sulfur
• B. Helium
• C. Oxygen
• D. Phosphorus

Answer 1

The correct option is D

Phosphorus

Explanation for correct option

(D) Phosphorus

Molecules and their Atomicity

• Molecules are a group of atoms bound together, constituting the smallest fundamental unit of a chemical compound that may take part in a chemical process.
• On the basis of atomicity, molecules can be categorized.
• Atomicity is monoatomic if only one atom is present, diatomic if there are two atoms present, triatomic if there are three atoms present, and so on.

Phosphorus

• Phosphorus is a chemical element with the atomic number $15$ and its atomic symbol is $\mathrm{P}$.
• White phosphorus and red phosphorus are the two primary forms of elemental phosphorus.
• Phosphorus is unable to form pi bonds due to its large atomic size.
• It exists as ${\mathrm{P}}_4$.
• It is tetratomic, with each $\mathrm{P}$ atom joined by a sigma bond to the other three $\mathrm{P}$ atoms.

Explanation for incorrect options

(A) Sulfur

• Sulfur exists as ${\mathrm{S}}_8$.
• Sulfur molecules have eight atoms.
• It is polyatomic.

(B) Helium

• Helium exists as $\mathrm{He}$.
• Helium has on atoms.
• It is monoatomic.

(C) Oxygen

• Oxygen exists as ${\mathrm{O}}_2$.
• Oxygen molecules have two atoms.
• It is diatomic.

Therefore, the correct option is (D) Phosphorus.