For statements (I) and (II), state for each if they are true or false. (I) When a bromine atom gains an electron, it becomes a negatively charged ion. (II) A neutral atom has equal numbers of protons and neutrons. If both are true, state if (II) is a correct explanation for (I).
Ions are simply charged chemical species. So, if this statement is true, this would be the chemical equation that would describe the process of a bromine atom gaining an electron to form a negatively charged ion. So, does this equation make sense for this process? Well, atoms are always neutral overall. And electrons have a negative charge. So, a neutral species plus a negatively charged species should result in a negatively charged ion. So, statement (I) is true. When a bromine atom gains an electron, it does become a negatively charged ion.
The second statement says that a neutral atom has equal numbers of protons and neutrons. Well, protons are positively charged particles, and neutrons are neutrally charged. If an atom is neutral, that means that it must have an equal amount of positive charge and negative charge. And, of course, the positively charged particles in atoms are protons, and the negatively charged particles in atoms are electrons. So, for a chemical species to be neutral, like a neutral atom, it must have equal numbers of protons and electrons, not protons and neutrons. So, that means that statement (II) is false.
Now, that it isn’t to say that a neutral atom can’t have equal numbers of protons and neutrons. Carbon-12, an isotope of carbon, has six protons, six neutrons, and six electrons. And it is a neutral atom. But two other isotopes of carbon, carbon-13 and carbon-14, also are neutral atoms, but they do not have equal numbers of protons and neutrons. What makes them neutrals is that they have equal numbers of protons and electrons. And since statement (II) was false, we don’t need to answer the last part of the question.