Strong trading kingdoms emerge in w. africa because of an abundance of salt and ?

Consider the model of the oxygen cycle on earth. the majority of earth's oxygen reservoirs are found in the a) atmosphere. b) biosphere. c) hydrosphere. d) lithosphere.

20. in humans, freckles are dominant to no freckles. trey has no freckles and his wife anna grace has freckles, but her dad doesn't. they want to know what percentage of their kids would look like trey. show a punnett square to support your answer.

Which of the following particles always has a positive charge? a. electronb. neutron c. proton d. ion