What are the reactions of electron transport chain and respiratory chain?

The electron transport chain consists of a series of redox reaction in the form of complex I, Q, complex II and III.

1- complex I establishes hydrogen gradient across the matrix by transferring two hydrogen ions plus its uses FMH as a cofactor.

2- In Q and complex II series, Q is reduced by NADH into QH2 and this complex receives FADH2 which delivers electrons to ETC.

3- The third complex is composed of cytochrome b and c.It also transfers protons to the fourth complex.

4- The Fourth complex contains cytochrome proteins c, a, and a3. It reduces oxygen which picks up the protons to form water.

Overall series of reactions in ETC:

NADH+H+ → Complex I → Q → Complex III → cytochrome c → Complex IV  → H2O

                     ↑

                 Complex II  

                     ↑

                 Succinate  

Respiratory chain:

1- Hydrogen is obtained by the reduction of NADH and from FADH.

2- The electrons are transferred to complexes I, II and III and then to oxygen.

3- After this complexes, I, II and III expel protons across the membrane.

4- These protons are then used to synthesize ATP.

answer is: c. the experiment shows that the red substance experienced a chemical change.

this is chemical change (chemical reaction), because two new substances are formed (metalig liquid and gas), the atoms are rearranged and the reaction is followed by an energy change.

this is example of chemical decomposition.

chemical decomposition (analysis) is the separation of a single chemical compound into its two or more elemental parts or to simpler compounds.  

chemical decomposition is opposite of chemical synthesis.