The end of the last snowball Earth phase roughly coincides with
A) the beginning of the Cambrian period which produced an explosion in diversity of life
B) the appearance of modern hominids
C) migration of life from the oceans onto land
D) the appearance of the dinosaurs
A
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Explain how environmental changes lead to biological evolution, mutation, and natural selection
What will be an ideal response?
Which of the following order from largest to smallest is incorrect?
a. void, supercluster, star b. filament, planet, asteroid c. wall, star, planet d. void, solar system, cluster
The ____________________ theory describes pulsars as rotating neutron stars with strong magnetic fields that confine high-speed charged particles in two beams emanating from the magnetic poles of the neutron star
Fill in the blank(s) with correct word
The H-R diagram main-sequence of stars has a limit at the lower-mass or energy-output end because
a. low-mass stars form from the interstellar medium very rarely. b. low-mass objects are composed primarily of solids, not gases. c. pressure does not depend on temperature in degenerate matter. d. the lower limit represents when the radius of the star would be zero. e. there is a minimum temperature for hydrogen nuclear fusion (the definition of a star).