Which is a component of john dalton’s atomic theory?
a. the ratio of atoms in a compound can vary.
b. the atoms of a single element differ.
c. an atom is a small particle that cannot be broken down.
d. atoms of different elements can be identical.

Which function is performed by earths atmosphere? a. ultraviolet rays are prevented from reaching the ozone layer. b. earths temperature is raised and moderated by trapping in heat c. charged particles from the sun are prevented from reaching earth. d. magnetic charges from space are prevented from reaching earths surface.

Which traits do human embryos have that link them to a common ancestor with fish and reptiles? a. scales and tail b. gill slits and scales c. tail and gill slits d. hair and tail

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.