Atomic mass comparison: Relative to oxygen, the atomic mass of nitrogen is ________.

Introduction / Context:
Atomic masses are fundamental constants used in chemical stoichiometry, gas property evaluation, and conversion between molar and mass-based quantities. Comparing nitrogen and oxygen is common because air is mainly composed of N2 and O2.

Given Data / Assumptions:

• Standard atomic masses: N ≈ 14, O ≈ 16 (on the 12C = 12 scale).
• Comparison is per atom, not per molecule.
• No isotope effects considered.

Concept / Approach:
Atomic mass of nitrogen (≈14) is smaller than that of oxygen (≈16). Therefore, on a molar basis, nitrogen-containing gases tend to have lower molar masses than comparable oxygen-containing gases, affecting densities and specific gas constants R = R_u/M.

Step-by-Step Solution:

Verification / Alternative check:
Air’s mean molar mass (~28.97 kg/kmol) reflects dominance of N2 (28) with O2 (32), consistent with nitrogen’s lower atomic mass.

Why Other Options Are Wrong:

• Equal to/more than: Contradict tabulated atomic masses.
• Varies with temperature: Atomic mass is a constant; temperature affects state, not mass.

Common Pitfalls:
Confusing atomic mass with molecular mass (e.g., N2 = 28 vs O2 = 32).

Final Answer:
less than