This equation shows the reaction that occurs when calcium carbonate decomposes. what type of reaction is it? CaCO3 + energy – CaO + CO2

a. endothermic
b. synthesis
c. replacement
d. exothermic

it's when something is going so fast it makes a loud noise, breaking the sound barrier, for example: a jet makes a loud noise, not only cause of the jet but because they reached a point where they went so fast that you can year the noise from various parts, kinda like a police car, lets say the car was going   so fast that you hear the siren of the cop car right next to you, but the car is probably a mile a way, it's cos the siren was next to you a few seconds if you understand me

b. a lightning bug, plug of grass, and a worm