Which of the following represents an ion?

a. a particle having 14 protons, 14 neutrons, and 14 electrons
b. a particle having 9 protons, 9 neutrons, and 10 electrons
c. a particle having 19 protons, 21 neutrons, and 19 electrons
d. a particle having 1 proton, 3 neutrons, and 1 electron

usually atoms are neutral. neutral atoms have an equal number of protons and electrons. protons are positively charged and electrons are negatively charged therefore when there are equal numbers of protons and electrons, net charge of the atom is neutral. Ions are when atoms either take in electrons or give out electrons. if the atom takes in electrons, then theres a higher number of electrons than protons and if an atom gives out electrons then theres more protons and electrons. Unbalanced number of electrons and protons results in a charged ion.  
the option where protons and electrons arent equal are B. 9 protons 9 neutrons and 10 electrons