AC-HPAT Prep| 188 Actual Questions and Answers
100% Correct| Latest Update 2025/2026
What is an atom? โโAn atom is the basic unit of an element. It is composed of a nucleus and one
or more electrons moving around it.
What is an electron? โโA negatively charged subatomic particle.
What is a proton? โโa stable subatomic particle occurring in all atomic nuclei, with a positive
electric charge equal in magnitude to that of an electron, but of opposite sign.
The number of protons in an atom indicates: โโThe atomic number.
What is the mass number? โโThe sum of protons and neutrons in the nucleus of the atom.
What is the atomic number? โโThe number of protons int the atom, specific for each element.
What is an isotope? โโAtoms of the same element that have the same number of protons, but a
different number of neutrons. They have identical chemical properties, but different physical
properties.
What is the atomic mass? โโThe weighted average of an isotope's masses.
What is the mass number of an atom with 60 protons, 60 electrons, and 75 neutrons? โโ135
What is the atomic number of an atom with 17 protons, 17 electrons, and 20 neutrons? โโ17
An atom with an atomic number of 58 and an atomic mass of 118 has how many neutrons? โโ60
