What defines an atom’s mass number? 👤 By The Quiz Wire Editorial Team 🌐 Source Chemistry Knowledge Base ✅ Fact Checked 📊 Difficulty Medium 📅 Last Updated 01 Dec 2025 A. Ionization energy B. Atomic number C. Sum of protons and neutrons D. Valence shell Check Answer 💡 Explanation: The mass number is the total number of protons and neutrons in an atom's nucleus. 📚 Topics: Chemistry Science 🎯 Exams: CSS GEN NTS PMS
