- The number of elementary entities in a mole. This numeric value is approximately 6.022142 × 1023. For instance, a mole of carbon-12 has approximately 6.022142 × 1023 atoms, and has a mass of 12 grams. Also known as Avogadro's constant. Its symbol is NA, or L.
- synonymAvogadro's constant
- Abbreviation of numerical aperture 2. Same as N/A.
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