Final answer:
The element with a molar mass of 30.974 g/mol is phosphorus. Molar mass corresponds to the mass of one mole of a substance, which contains Avogadro's number of particles.
Step-by-step explanation:
The element with a molar mass of 30.974 g/mol is phosphorus (P). The concept of molar mass is significant in chemistry, as it relates the mass of the substance to the number of molecules or atoms. One mole of a substance corresponds to 6.022 × 10²³ particles (Avogadro's number), whether they're molecules, formula units, or atoms. The molar mass in grams per mole (g/mol) is numerically equal to the average atomic mass of the element.
In this case, a quick examination of the periodic table will reveal that phosphorus has an atomic mass very close to 30.974 amu, which corresponds to its molar mass in grams. Hence, 1 mole of phosphorus atoms has a mass of 30.974 g and contains 6.022 × 10²³ atoms of phosphorus.