How are elements arranged on the periodic table? By Kalsoom Tahir 🌐 Source Chemistry Knowledge Base ✅ Fact Checked 📊 Difficulty Easy 📅 Last Updated 13 Aug 2026 A. Atomic mass B. Atomic radius C. Increasing atomic number D. Valence electrons Check Answer 💡 Explanation: The modern periodic table is ordered by the number of protons (atomic number). 📚 Topics: Chemistry Science 🎯 Exams: CSS GEN NTS PMS