Answer:

Explanation:
Alkaline earth metals are in group 2. The number of valence electrons of elements in group 2 is 2.
Answer:
One that “Can be answered by conducting an experiment”
Explanation:
B. When electrons gain energy, they have the power to move up to a higher energy level in an atom.
Answer:
<em>The correct option is B) a gradual change of the traits of a species over time</em>
Explanation:
The theory of natural selection explains the gradual changes which occur in the population of a species over time. According to natural selection, those organisms which are better adapted to live in an environment survive and pass on their traits to their offsprings. As a result, the traits of a species tend to change over time through the process of evolution. Evolutionary changes do not occur rapidly, instead, they can take many years to occur.