Part A Many reactions that are thermodynamically possible do
Solution
Answer Part A) it means that the molecules that ought to react would RELEASE energy if they were to do so, BUT THEY DO NOT POSSESS enough energy to collide in a way that allows the reaction to be INITIATED.
Reason- As we know, In case of a chemical reaction, the Activation energy is provided from the external environment for a reaction to occur. and the molecules that out to react must release the energy by themselves to initiate a reaction. but the reactants (molecules that ought to react) do not possess enough energy to initiate a reaction by themselves because such reactions are catalyzed by enzymes.
Answer Part D) Appropriate statements about each are given below;
Reason- As we know that Enzymes are highly specific for their reactants and are highly controlled for their activity. but their PH and temperature range of action is very narrow. while much energy is required for synthesis of the catalyst which may have broad PH and temperature range of action.

