An oxygen molecule present in air consists of how many atoms bonded together in its most stable form?

Introduction / Context:
In basic chemistry, students learn that elements can exist as individual atoms, as molecules containing a fixed number of atoms, or as extended networks. The form in which an element exists under standard conditions affects its chemical and physical properties. This question asks about the molecular form of oxygen in the air we breathe, which is fundamental to understanding combustion, respiration, and many chemical reactions.

Given Data / Assumptions:
- The element is oxygen in its most stable form present in the Earth atmosphere at normal conditions.
- We are dealing with the ordinary oxygen used in breathing and combustion, not special allotropes like ozone.
- The options describe molecules with one, two, three, or many atoms: monoatomic, diatomic, triatomic, and polyatomic forms.
- Standard school level chemical notation is assumed, with O2 representing molecular oxygen.

Concept / Approach:
Atmospheric oxygen exists primarily as diatomic molecules, written as O2. Each O2 molecule contains two oxygen atoms chemically bonded together. This diatomic form is more stable than monoatomic oxygen under normal terrestrial conditions. Another allotrope, ozone, has the formula O3 and is triatomic, but it makes up only a tiny fraction of the atmosphere and is concentrated in the ozone layer. Therefore, when a general question refers to an oxygen molecule in air, it almost always refers to O2, making oxygen diatomic.

Step-by-Step Solution:
Step 1: Recall the chemical symbol for molecular oxygen in air, which is O2. Step 2: Interpret O2 as a molecule made up of two oxygen atoms bonded together. Step 3: Recognise that monoatomic oxygen, O, is a highly reactive species that is not the dominant form in the atmosphere. Step 4: Recognise that ozone, O3, is triatomic oxygen and exists in much smaller amounts compared to diatomic oxygen. Step 5: Compare with the answer choices and select the option that describes diatomic oxygen as two atoms bonded together.

Verification / Alternative check:
Chemistry textbooks and environmental science resources consistently state that approximately twenty one percent of the atmosphere by volume is oxygen, and that this oxygen is present chiefly as O2 molecules. Gas law problems also treat oxygen as diatomic when calculating molar masses, using 32 grams per mole, which corresponds to two oxygen atoms in each molecule. The small fraction of atmospheric ozone, while important for absorbing ultraviolet radiation, is explicitly identified as O3 and not as the standard form. These references confirm that oxygen in air is diatomic, not monoatomic or triatomic in bulk.

Why Other Options Are Wrong:
One atom (monoatomic): This would be correct for noble gases such as helium or neon, but not for the molecular form of oxygen in air.
Three atoms (triatomic): This describes ozone, O3, which is an allotrope of oxygen found in much smaller quantities, not the main atmospheric form.
A large number of atoms (polyatomic): This description fits network solids such as diamond or silica, not the simple molecules of oxygen gas.

Common Pitfalls:
Some learners confuse the terms oxygen and ozone because both relate to the same element and are involved in atmospheric processes. They may mistakenly think that ordinary oxygen is triatomic. Another pitfall is to focus too much on the idea that oxygen supports combustion and incorrectly assume that more atoms in a molecule always mean more reactivity. To avoid these errors, remember the standard chemical formulas: O2 for the oxygen we breathe and O3 for ozone in the stratosphere.

Final Answer:
An oxygen molecule in air is Diatomic, consisting of Two atoms (diatomic) bonded together in the stable form O2.