Which of the following statements about the composition of earths atmosphere is true?
a)earths atmosphere contains 78% water vapor which is essential to life.
b)earths atmosphere contains 21% oxygen.
c)earths atmosphere contains carbon dioxide which all life forms require.
d)earths atmosphere allows radiation from the sun to pass through it and warm earths surface.

With the word calcite wich completes the analogy mineral, erosion, marble, or aragonite

Which of the following factors would not contribute to allopatric speciation? a) a population becomes geographically isolated from the parent population.b) the separated population is small, and genetic drift occurs.c) the isolated population is exposed to different selection pressures than the ancestral population.d) different mutations begin to distinguish the gene pools of the separated populations.e) gene flow between the two populations is extensive.

When rutherford performed his metal foil experiment, he was surprised that most of the alpha particles