In what sense is all observable deuterium "primordial"? Why is its abundance so important in cosmology?
What will be an ideal response?
Deuterium is created in stellar cores now, but just as quickly consumed in the making of helium on the main sequence. So any free deuterium must be left over from primordial nucleosynthesis; its survival means that the matter density could not have been anywhere near critical.
You might also like to view...
Based on current observations, ____ has a heavy element core, and a very compressed liquid layer and atmosphere both made mostly of hydrogen
a. Jupiter b. Pluto c. Venus d. an asteroid e. a meteor
Length Contraction: Astronaut Hans leaves Earth in a spaceship traveling at a speed of 0.280c relative to the observer Brian at rest on Earth. Hans is holding a pencil at an angle of 30° with the direction of travel, as seen by Hans. What angle does the pencil make with the direction of travel, as seen by Brian on Earth?
A. 29° B. 30° C. 31° D. 33° E. 90°
In general, wind direction ________ between adjacent bands in Jupiter's atmosphere
Fill in the blank(s) with correct word
What would be the best explanation for the fact that most natural water has a pH of about 5.6?
A) Carbon dioxide reacts with water to form an acid. B) Air contains acid rain particles. C) Minerals that are dissolved in water are often acidic. D) Many salts that dissolve in natural waters make the water basic. E) none of the above