4. based on your knowledge of the relationship between the burning of fossil fuels and co2, give another
reason for the cyclic nature of co2 concentrations throughout the year.

7. according to the theory of isostasy, which statement must be true? a. the asthenosphere is denser than the lithosphere. b. the asthenosphere has the same density as the lithosphere. c. the lithosphere has the same density as the core. d. the lithosphere is denser than the asthenosphere.

The primary agent of contact metamorphism is

[ou.01jthe greatest speed with which any physical object moves is 300,000 km/soundsec. which of the following has a speed of 300,000 km/sec? a.light in water b.light in vacuum c.sound in air. d. sound in water