* Atomic Mass: Atomic mass is a measure of how much an atom of a particular element weighs. Hydrogen has the smallest atomic mass of all the elements.

* Molecular Weight: When elements combine to form molecules, we consider their molecular weight. Even though hydrogen typically exists as a diatomic molecule (H2), its molecular weight (2 atomic mass units) is still significantly less than the molecular weights of the other options.

Here's a comparison of the approximate atomic masses:

* Hydrogen (H): 1 atomic mass unit

* Nitrogen (N): 14 atomic mass units

* Oxygen (O): 16 atomic mass units

* Carbon (C): 12 atomic mass units

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