What sort of nucleophile does nadh supply?

Hydride ion

Explanation:

You often see the reduction with NADH written as

NADH ⟶ NAD⁺ + H⁺ + 2e⁻

If you think about it, H⁺ + 2e⁻ is equivalent to H:⁻, so we could write the reaction as

NADH ⟶ NAD⁺ + H:⁻

In terms of a mechanism, the dihydropyridine ring of NADH transfers a hydrogen atom with its pair of electrons (a hydride ion) to the substrate and becomes the more stable, aromatic pyridinium ion in NAD⁺.

answer; ///i do believe that the correct answer is (b); ///particle composed of two or more atoms bonded together;

definition

                    entropy is a measure of the randomness or the extent of disorder of a chemical process.

                      enthalpy is a measure of the heat change of a reaction occurring at a constant pressure.

measurement units:

                        entropy is measured in joule per kelvin (jk⁻¹)   whereas enthalpy is measured in joule per mole (jmol⁻¹)

requirements:

                            entropy has no requirements or limits, and its change is measured by the division between the heat change of the chemical process and the temperature.

                              in contrast, enthalpy can only be related to the heat change of the reaction under standard conditions.