Which of the following correctly lists the particles in order from least massive to most massive. A. electron, proton, hydrogen atom, helium atom
B. proton, electron, hydrogen atom, helium atom
C. proton, helium atom, hydrogen atom, electron
D. hydrogen atom, electron, helium atom electron

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.

Structure of the atoms: discovery of the nucleus in 1909i need answering all of these questions

I’m an electrically neutral atomic any element, there are equal numbers of