How do we know that some interstellar matter is dust?
A. We can observe the tiny particles with the Hubble Space Telescope.
B. Dust obscures and reddens starlight.
C. Interstellar matter is composed only of hydrogen gas.
D. Dust emits X-rays.
Answer: B
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When an igneous rock is melted and then re-solidifies it turns into
A) a meteorite B) a sedimentary rock C) another igneous rock D) a metamorphic rock
The maximum volume of sediment a stream can carry is dependent on the stream's
A) laminar flow. B) velocity. C) discharge. D) channel geometry.
What is the typical main sequence lifetime of a B-type star?
A) less than a million years B) 20 million years C) 100 million years D) 1 billion years E) 10 billion years
A diffraction grating has 6 700 lines/cm. What is the slit separation?
a. 6.7E–3 m b. 1.5E–6 m c. 1.5E–9 m d. 6.7E–7 m e. Not enough information