How many protons and electrons in H3O?

Well, honey, in the H3O+ ion, there are 3 hydrogen atoms, each bringing 1 proton and 1 electron to the party. So that's 3 protons and 3 electrons from the hydrogen atoms. Then you've got 1 oxygen atom, with 8 protons and 8 electrons. Add it all up, and you've got a total of 11 protons and 11 electrons in the H3O+ ion.