(A). As the normal oxygen atom is neutral, thus, the charge on the normal oxygen atom is zero.
Thus, the value of charge, in this case, is zero.
(B). The electron is a negatively charged fundamental particle.
Thus, the charge on the electron is negative.
(C). The nucleus is surrounded by negatively charged electrons to make the net charge on the atom zero.
Thus, the charge on the nucleus is positive.
(D). The neutrons are neutral in behavior. T