Solution:

The electron transport chain (ETC) is a series of protein complexes that transfer electrons and protons across the inner mitochondrial membrane, leading to the generation of a proton gradient that drives ATP synthesis by ATP synthase. In the process, NADH and FADH2 are oxidized, and oxygen is reduced to form water.

Given that five molecules of water are produced in ETS of mitochondria, we can calculate the number of ATP produced and NADH2 oxidized as follows:

1. Number of electrons needed to produce five water molecules:
- Each water molecule is formed by the combination of two electrons from the ETC with two protons from the matrix.
- Therefore, five water molecules require 10 electrons (5 x 2).

2. Number of ATP produced per electron:
- The exact number of ATP produced per electron depends on the specific ETC complex and the proton motive force generated by the electron transport.
- On average, oxidative phosphorylation produces about 2.5 ATP per electron transferred from NADH to oxygen and about 1.5 ATP per electron transferred from FADH2 to oxygen.
- Since we don't know the source of the electrons that produced the water molecules, we can assume an average of 2 ATP per electron.

3. Number of NADH2 oxidized:
- Each NADH molecule donates two electrons to the ETC, so we need five NADH2 molecules to supply the 10 electrons required to produce five water molecules.

Therefore, the answer is (b) 10 ATP and 5 NADH2 oxidized.

- 10 electrons from 5 NADH2 molecules are used to produce 10 ATP.
- The remaining 4 electrons are used to produce 2 water molecules and reduce 2 oxygen molecules.
- The 5th NADH2 molecule donates its electrons to the ETC to produce the remaining 3 water molecules.
- A total of 5 NADH2 molecules are oxidized to supply the 10 electrons needed for water production.

Note: This calculation assumes that all the ATP produced goes through oxidative phosphorylation, which is not always the case in mitochondria. Some ATP can be produced by substrate-level phosphorylation or other mechanisms. However, based on the information given in the question, we can only calculate the maximum possible ATP yield from the five water molecules produced.

30 atp and 10 nadh2