(PLEASE ANSWER ASAP) What is defined as the energy required to start a chemical reaction?

A:precipitate energy

B:heat

C:reactant energy

D:activation energy

What is driving behind plate tectonics (plate movment)? a) gravity only b) inertia c) convection and gravity d) the sun theres no option for science so i picked chemistry. plz

Quiz1. which physical state of nitrogen has the highest entropy? a solid© b gasoc liquid

Answer asap need by wednesday morning explain how a buffer works, using an ethanoic acid/sodium ethanoate system including how the system resists changes in ph upon addition of a small amount of base and upon addition of a small amount of acid respectively. include the following calculations in your i. calculate the ph of a solution made by mixing 25cm3 0.1m ch3cooh and 40cm3 0.1m ch3coo-na+. [ka = 1.74 x 10-5 m] ii. calculate the ph following the addition of a 10cm3 portion of 0.08 m naoh to 500cm3 of this buffer solution. iii. calculate the ph following the addition of a 10cm3 portion of 0.08 m hcl to 200cm3 of the original buffer solution.