Atomic mass in 12 grams of the carbon isotope C-12. The number of atoms in a mole is called Avogadro's number, the value of which is approximately 6.022 × 10. One mole of a substance always contains almost exactly the "standard atomic weight" or "molar mass" of that substance; however, this may or may not be true for the "atomic mass," depending on whether or not the element exists naturally in more than one isotope. For example, the standard atomic weight of iron is 55.847 g/mol, and therefore one mole of iron as commonly found on earth has a mass of 55.847
Standard weight in fish relationships representing a species across its range are used. As fish grow in length, they increase in weight. The relationship between weight and length is not linear. The relationship between length ("L") and weight ("W") can be expressed as: When the equation is for standard weight, the standard weight for a given length is written as W. The exponent "b" is close to 3.0 for most species. The coefficient "a" varies between species. If the exponent "b" is greater than three for a certain fish species, that species tends to become relatively fatter or have more girth as it grows