If the substance being oxidized is in direct contact with the substance being reduced, what will be produced?
a. mass
b. heat energy
c. friction energy
d. potential energy

The correct option is D. When an oxidant and a reductant are in direct contact, a potential energy is generated whose value is determined by the potential differences between the valence electrons in atoms of the participating elements. The oxidant is the species that gains electrons and is reduced in the process while the reductant is the specie that loses electrons and is oxidized in the process. 

Theoretical temperature at which molecules stop moving and no more heat can be removed from the object. kelvin: absolute zero degrees. none of the above.

Mg-26 and mg-24 are pair of isotopes. isotopes are defined as atoms of the same element having same atomic number but different mass number. i hope that was .