Answer:
More on Newton's Law of Universal Gravitation. ... Newton proved that the force that causes, for example, an apple to fall toward the ground is the same force that causes the moon to fall around, or orbit, the Earth. This universal force also acts between the Earth and the Sun, or any other star and its satellites
Explanation:
This is due to the fact that akyl caborcation, that is formed, is more stable hence the reaction is also faster. Alkenes are more reactive that alkynes (that give vinyl caborcation) towards nucleophilic addition. This is attributed to the linear structure of alkynes, that has a higher surface for reactions, that the planar structure of alkenes.
The correct answer is: B) -20 kcal/mol
Enzymes are catalysts of chemical reactions, they speed up the reaction by lowering the activation energy, but don't affect the ∆G (change of Gibbs free energy). The changes in free energy occurs due to change in concentrations of reactants and products and don't have anything to do with the presence or absence of an enzyme.