Lux-Flood concept is a dono-acceptor system of

Explanation

The Lux-Flood concept defines acids and bases in terms of their ability to donate or accept oxide ions (O2-). According to this concept, a Lux-Flood acid is a substance that donates oxide ions, while a Lux-Flood base is one that accepts them. This is particularly applicable in high-temperature reactions involving metal oxides. The other options are incorrect as they refer to different acid-base theories: protons are involved in the Brønsted-Lowry theory, electron pairs in the Lewis theory, and neutrons do not play a role in any acid-base concepts.