What is the mass number of an atom which contains 21 electrons,21 protons and 24 neutrons

Which of the following elements would you expect to have the lowest ionization energy value? fluorine, lithium, neon, nitrogen

The big bang nucleosynthesis theory states that elements were produced in the first few minutes of the big bang while elements have their origins in the interiors of stars, forming much later in the history of the universe.

Which process transfers heat from inside earth to its surface? convection currents in mantle pulling away of tectonic plates drawing in of tectonic plates convection currents in crust