Is nh3 a molecular crystal, metal, ionic crystal, or a network solid?

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.

Idon't really understand this can you me and show your work.☺☺[ chemistry b] subject [ electron transfer in lonic bonds]grade( 12)

The name of the ion, s2-, is: sulfurous ion sulfide ion sulfur ion sulfate ion