Yes, weight changes constantly as it moves through different parts of a gravitational field. However, its mass does not.
None Even electrons have weight
A chemical change in which electrons are gained is a reduction.
That depends on how you change the number of electrons.
The equivalent weight of sodium thiosulfate (Na2S2O3) is the molar mass divided by the change in oxidation state per mole of electrons transferred in a reaction. In this case, the equivalents of Na2S2O3 is equal to its molar mass (158.11 g/mol) divided by the change in oxidation state involved in the reaction it participates in.
Protons and neutrons are about the same weight. Electrons are far lighter than either protons or electrons.
no
the electrons gain a huge amount of energy
No. The vast majority of the weight of iron comes from things that are unaffected by the flow of electrons -- protons, neutrons, and bound electrons. Iron is packed full of movable electrons, but when electrons flow through it, just as many electrons enter one end as exit the other end. It's like a garden hose full of water -- it weights just as much when the water is practically motionless inside the hose as when the water is swiftly flowing through the hose, because there is the same amount of water inside the hose in both cases. The weight is constant during the flow and after the flow is turned off.
yes, electrons may change energy levels through a gain or loss of energy.
It will have 12 electrons.
Weight change = Final weight - Initial weight
No, the change in mass is generally not significant when an object gains or loses electrons because electrons have a very small mass compared to protons and neutrons in the nucleus. The change in mass from gaining or losing electrons is usually negligible.