One of the reasons that gold is a rare element is that:
A) it has a very low atomic mass.
B) it has a very low atomic number.
C) gold atoms were absorbed during supernova explosions.
D) gold atoms are made only by short-lived nuclear reactions.
Question 2
In their attempt to gauge the true shape of our Galaxy, the Herschels concluded that:
A) our Galaxy has a hexagonal shape.
B) the Sun is the only luminous star in our Galaxy.
C) the Sun and Earth are near the edge of our Galaxy.
D) our Galaxy has some noticeable holes lacking stars around its edges.