On the H-R diagram, 90 percent of all stars are ____
a. either giant or supergiant stars
b. white dwarfs
c. main sequence stars
d. sred dwarfs
e. binary stars
c
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A pure sample of 226Ra contains 3.0 × 10^14 atoms of the isotope. If the half-life of 226Ra = 1.6 × 10^3 years, what is the activity of this sample?
a. 13 × 10^10 decays/yr c. 6.7 × 10^9 decays/yr b. 9.4 × 10^10 decays/yr d. 8.7 × 10^10 decays/yr
Which of these, if used to replace gasoline as an automobile fuel, would not contribute to global warming?
A) Synthetic gasoline made from coal B) Electricity from a nuclear power plant C) Electricity from a coal-burning plant D) All of the above would contribute to global warming. E) None of the above would contribute to global warming.
A large vat contains 1.000 L of water at 20°C. What volume will this water occupy when it is heated up to 80°C? Water has a volume expansion coefficient of 210 × 10-6 K-1
A) 1.600 L B) 1.013 L C) 0.987 L D) 0.9987 L
Enceladus orbits Saturn in a resonance with the larger moon Dione. Each time Dione orbits Saturn once, Enceladus orbits _______________
Fill in the blank(s) with correct word