A sample of matter that contains atoms that all have the same number of protons is
a. an element.
b. a substance.
c. a compound.
d. a homogeneous mixture.
a
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____________ of hydrogen atom nuclei in the core replace the heat the Sun ____________ to keep it in equilibrium
a. Nuclear fusion reactions; loses into space b. Nuclear fusion reactions; gains from empty space c. Chemical reactions; loses into space d. Chemical reactions; gains from empty space e. Nuclear fission; loses into space
Why do some scientists say that the Moon may have been important for the evolution of human life?
A) It created the tides in the ocean, where life most likely started. B) It stabilized Earth's axis tilt and prevented large climate changes. C) Meteorites from the Moon were the seeds of life on Earth. D) It gave humans the inspiration to explore worlds beyond Earth. E) It most certainly wasn't—only lunatics would think so.
How does the best possible angular resolution of a telescope with a 10-meter diameter mirror compare to that of a telescope with a 5-meter diameter mirror?
A) The 10-meter telescope's angular resolution is better by a factor of 2. B) The 10-meter telescope's angular resolution is better by a factor of 4. C) The 10-meter telescope's angular resolution is better by a factor of 10.
Venus' clouds are water vapor and are similar to clouds in Earth's atmosphere
Indicate whether the statement is true or false