How many atoms are there in 1 mol of an element?

Which of these properties, used alone, would be least useful in identifying most minerals? a. color b. luster c. streak d. density

The wave shown on the electromagnetic spectrum disturb the medium it passes through a)different frequency. b)the same frequency .

Which of the following statements is true? a. elements in the last period are radioactive. b. atomic weight is the same as atomic mass. c. elements in the same group have the same number of electron shells. d. atomic number equals the number of neutrons in the nucleus of an atom.