Greenhouse gases make up what percentage of earth's atmosphere? a. less than 1% b. between 1% and 5% c. between 5% and 20% d. over 20%

Joseph has hypothesized that sound travels in waves. if he were following the scientific method, what should he do next? a. ask a question. b. test the hypothesis. c. study the results. d. tell other scientists about his hypothesis.

The wave shown on the electromagnetic spectrum disturb the medium it passes through a)different frequency. b)the same frequency .

The characteristic of two different types of reactions are shown below. reaction a: electrons are gained by the atoms of an element. reaction b: protons are lost by the atom of and element. which statement is true about the atoms of the elements that participate in the two reactions? a: their identity changes in both reaction a and b. b: their identity changes in reaction a but not b. c: their identity changes in reaction b but not a. d: their identity remains the same.