An atom contains 31 protons,39neutrons and 31 electrons. Identify the mass number of this atom

Drug abuse will not lead to physical and psychological dependence. true or false ?

16. in a reaction that has reached equilibrium, a. the forward and reverse reactions are occurring at the same rate. b. the reactants and products are in equal concentrations. c. the forward reaction has gone further than the reverse reaction. d. there are equal numbers of atoms on both sides of the equation. e. a, b, and d are correct.

An atomic nucleus is composed ofa)protons. b)protons and neutrons. c)protons and electrons. d)protons, neutrons, and electrons.