What element has mass number of 40
- What element has atomic mass of 40
- What element has a mass number of 40 and 20 electrons
- What element has a mass number of 40 and 20 protons
- What element has a mass number of 40 and 21 neutrons
- What element has mass of 40
- What element has 18 protons and has a mass number of 40
- What element has a mass of 40.08
- What element has molar mass of 40
- What element has a mass of 40 amu
- What element has an atomic number of 20 and mass number of 40
- What element on the periodic table has a mass number of 40
- What element has a mass number of 40.078 and an atomic number of 20
- What element has an atomic mass of 40 and an atomic number of 18