Answer:
The atomic number
Explanation:
Transmutation refers to the conversion of one chemical element into another. A transmutation usually involves a change in the structure of atomic nuclei and this may be induced by a nuclear reaction.
Transmutation was first achieved in 1919 by Lord Rutherford when he successfully changed a nitrogen nucleus to an oxygen-18 isotope, producing a proton in the process.
Since transmutation often involves changing one atom into another, the atomic number or mass number of the original element always changes (to form a new element) in the process.
The magnetic field is believed to be generated by electric currents in the conductive material of its core, created by convection currents due to heat escaping from the core. So your answer is A
You haven't attached any options but anyways, to help you with your question, elements belonging to the same group (e.g. alkali metals, noble gases) all have the same chemical properties. Hydrogen, for example, have the same properties with Sodium, Potassium and Lithium.
When an ion loses electrons, it becomes a positive ion even though it does not lose protons. If there are more protons than electrons in the ion, the ion will have a positive charge.