Solution

a) Exothermic reactions are those reactions in which heat or energy will be released. When we breathe out, our breath is warmer. This happens due to the respiration reaction of our body. Carbohydrates present in food are broken down by enzymes to form glucose. This glucose combines with oxygen in the cells of our body and provides energy. This reaction is known as respiration.hence, respiration is considered as an exothermic reaction. b) Oxidation is the process of loss of electrons or an increase in oxidation state of a molecule, atom, or ion. Reduction is the process of gain of electrons or a decrease in oxidation state of a molecule, atom, or ion. c) Oxidant is the substance which gains the electrons. Reductant is the substance which loses the electrons. Hence, Glucose is oxidized and oxygen is reduced.