C) iron cannot fuse with other nuclei to produce energy.
D) iron supplies too much pressure.
E) iron is in the form of a gas, not a solid, in the center of a star.
In the Kelvin scale, absolute zero lies at
A) zero K.
B) 273 degrees C
C) -373 degrees C.
D) Both A and B are correct.
E) Both A and C are correct.
Assuming the conditions ripe for life and intelligence abound in the Galaxy, what factor
limits the number of galactic civilizations currently in existence?
A) the lack of metals for technology
B) the number of supernova explosions
C) the expansion of the universe