Which of the following statements about physical models is not true? a. physical models are often three-dimensional representations. b. physical models are used to represent an object or event. c. physical models are usually in the form of a graph. d. physical models can be used to depict microscopic objects.

oxygen = 21% of the atmosphere

nitrogen = 78%

carbon dioxide = 0.1%

argon =0.934%

the correct answer is 4) heat and pressure

metamorphic rocks arise from transformation of existing rocks types, in a process called metamorphism. during metamorphism the original rock(prolith) change into metamorphic rock by heating (150-200c) and pressure of more than 1000 bar. the original rock can be sedimentary, igneous, or existing metamorphic rock.