The atmosphere exerts a force (pressure) on earth. why does the atmosphere exert pressure on earth?
a. because of the weight of air
b. because of the ozone layer
c. because of energy from the sun
d. because of the greenhouse effect

Use the drop-down menus to match each part of the scenario to the correct scientific practice. akira records the speed of a reaction without a catalyst and then with a catalyst. akira creates a reaction without a catalyst and repeats the reaction with a catalyst. akira turns in a written lab report to his science teacher. akira wonders, "will adding a catalyst speed up this chemical reaction? " akira writes in his notes that adding a catalyst sped up the chemical reaction because the catalyst lowers the activation energy needed to get the reaction started.