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Earth's atmosphere is unique among the planets and is able to support life because it contains a large amount of a) oxygen b) helium c) methane d) carbon dioxide

Which of the following sections on the sat presents the questions in order of difficulty, from easiest to hardest, within each question type? select all that apply. math test writing and language test reading test

Which of the following ideas did greek philosopher democritus contribute to the atomic theory? a. each object is made up of one atom, which varies in size from very small to very large. b. matter is composed of only one kind of particle, which can be easily destroyed. c. every element has a specific type of atom, which remains the same size in all forms of matter. d. all matter is composed of small particles, which combine to make larger objects.