What is the atomic number, mass number, and charge, respectively, of the atom or ion represented?

Question

Quizplus · Accepted Answer

The given symbol represents an ion, as it has a charge indicated. The number before the "H" represents the mass number, which is the sum of protons and neutrons in the nucleus. The number before the "He" represents the atomic number, which is the number of protons in the nucleus. To find the charge, we need to compare the number of electrons (which are negative) to the number of protons (which are positive).

From the symbol given, we can see that there are 2 protons (since the atomic number is 2, which is the number of protons in an atom of helium) and 2 neutrons (since the mass number is 4 and the atomic number is 2, which means there must be 4-2=2 neutrons). Therefore, the mass number is 4. The charge is indicated by the superscript on the right side of the symbol, which in this case is 0. This means that the number of protons (+2) and electrons (-2) is equal, resulting in a net charge of 0.

Therefore, the correct answer is C.

What Is the Atomic Number, Mass Number, and Charge, Respectively