Number of ATP Produced:
- In the Electron Transport Chain (ETS) of mitochondria, the production of ATP occurs through oxidative phosphorylation.
- For every molecule of NADH2 that is oxidized in the ETS, approximately 2.5 molecules of ATP are produced.
- Since NADH2 is produced during the oxidation of glucose in glycolysis and the Krebs cycle, we need to determine the number of NADH2 molecules that are oxidized to produce 5 molecules of water.

NADH2 Oxidation:
- The oxidation of NADH2 occurs in the ETS through a series of redox reactions.
- During this process, NADH2 donates its electrons to the electron carriers in the ETS, such as flavin mononucleotide (FMN) and coenzyme Q (CoQ).
- As the electrons pass through the ETS, they create a proton gradient across the inner mitochondrial membrane.
- This proton gradient is then utilized by ATP synthase to synthesize ATP from ADP and inorganic phosphate.
- The electrons ultimately combine with molecular oxygen (O2) to form water (H2O), which is the final product of the ETS.

Calculation:
- Since the production of 5 molecules of water requires the oxidation of 10 electrons, we can conclude that 10 molecules of NADH2 are oxidized in this process.
- Therefore, the number of ATP molecules produced can be calculated by multiplying the number of NADH2 molecules oxidized by the conversion factor of 2.5 ATP molecules per NADH2 molecule.
- Hence, the number of ATP produced is 10 NADH2 molecules * 2.5 ATP molecules/NADH2 molecule = 25 ATP molecules.

Conclusion:
- In the given scenario, where 5 molecules of water are produced in the ETS of mitochondria, the number of ATP molecules produced is 25, and 10 molecules of NADH2 are oxidized.
- This highlights the importance of the ETS in generating ATP through oxidative phosphorylation and demonstrates the role of NADH2 as an electron carrier in the process.