28. How many atoms are there in 69.7 g of nickel?

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.

In a water molecule, hydrogen and oxygen are held together by a(an) bond. a) double covalent b) ionic c) nonpolar covalent d) hydrogen e) polar covalent

The number at the end of an isotope’s name is the number.