Based on current evidence concerning the amount of deuterium in the universe, we can conclude that
A) ordinary (baryonic) matter makes up most of the mass of the universe.
B) neutrons greatly outnumber protons in the universe.
C) most of the deuterium that was created during the era of nucleosynthesis has since been destroyed.
D) the density of ordinary (baryonic) matter is between 1 percent and 10 percent of the critical density.
E) we live in a critical-density universe.
D
You might also like to view...
The figure shows a cross section of three parallel wires each carrying a current of 24 A. The currents in wires B and C are out of the paper, while that in wire A is into the paper. If the distance R = 5.0 mm, what is the magnitude of the force on a 4.0-m length of wire A?
a.
15 mN
b.
77 mN
c.
59 mN
d.
12 mN
e.
32 mN
Suppose that you measure the parallax angle for a particular star to be 0.5 arcseconds. What is the distance to this star?
A) 0.5 light-year B) 0.5 parsec, which is about 1.63 light-years C) 5 light-years D) 5 parsecs, which is about 16.3 light-years E) 2 parsecs, which is about 6.52 light-years
The diagram above shows the life track of a 1 MSun protostar from the time it first begins to form until it reaches the main sequence, with four stages labeled. What is happening to the protostar's surface temperature and luminosity during Stage 1, when gravity assembles the protostar from a collapsing cloud?
A) Its surface temperature and luminosity increase. B) Its surface temperature remains the same and its luminosity decreases. C) Its surface temperature and luminosity decrease. D) Its surface temperature decreases and its luminosity increases. E) Its surface temperature and luminosity remain the same.
All of the following have occurred over long periods of time on Earth. Which one is not thought to have played a major role in long-term changes in Earth's climate?
A) changes in the Earth's axis tilt B) changes in the Earth's overall reflectivity C) a gradual rise in the atmospheric content of oxygen D) changes in the atmospheric concentration of greenhouse gases