The δg for a particular enzyme-catalyzed reaction is -20 kcal/mol. if the amount of enzyme in the reaction is doubled, what will be the δg for the new reaction?

The value of the of ΔG for the new reaction will be same as the given value of -20kcal/mol.

Explanation:

In an enzyme-catalyzed reaction, the concentration or amount of enzyme will not affect the equilibrium constant of the reaction due to which ΔG for the reaction will remain unaffected. Here enzymes are acting as a catalyst that cannot alter law thermodynamics and equilibrium of the reaction.

Since the enzyme amount will not affect the equilibrium of the reaction, the value of ΔG will remain the same as given -20 kcal/mol.

c. because step up transformer steps up the input voltage i.e increases the input voltage  

the number of turns are greater on the secondary side of step up transformer  

transformer does not handle dc current