Can oxidation or reduction take place alone why or why not what are such reaction called?

Oxidation and reduction cannot occur independently; they are intrinsically linked processes known as redox reactions. In oxidation, a substance loses electrons, while in reduction, another substance gains those electrons. This interdependence is due to the conservation of charge, meaning that for one species to lose electrons (oxidation), another must gain them (reduction). Thus, redox reactions always involve both processes simultaneously.