Which statement about exothermic reactions is correct?
a. Energy is always created in the form of heat.
B. Energy is transferred from the surroundings to the reactants.
C. Energy is used to force electrons to move to higher energy levels.
D. Energy is transferred from the reactants to the surroundings.

Naoki's bicycle has a mass of 10 kg. if naoki sits on her bicycle and starts pedaling with a force of 168 n, causing an acceleration of 2.8 m/s2, what is naoki's mass?

Maria wants to determine which type of disinfectant kills the most bacteria. which of the following is the best way for maria to determine this? a. ask ten different companies that make disinfectants which type is best. b. put the same amount and species of bacteria on ten identical plates, and add ten different kinds of disinfectant to each plate. c. interview ten different people to determine which type of disinfectant they prefer. d. put the same amount and species of bacteria on ten identical plates, and add a different disinfectant to each plate.

Which property of a rock remains unchanged by mechanical weathering? a. total surface area b. size and shape c. mineral composition d. sharpness