Answer:
Helium is in group 18 of the periodic table. How is helium different from the other elements in this group? = Helium atoms have 2 valence electrons, while atoms of the other elements in the group all have 8 valence electrons.
An emission spectrum will occur when = An electron releases energy and falls back to a lower energy level.
Explanation:
Another type of weathering that attacks rocks is chemical weathering, a process that breaks down rock through chemical changes. The causes of chemical weathering include action of water, oxygen, carbon dioxide, living organisms, and acid rain. Chemical weathering can produce new minerals as it breaks down rock.
Explanation:
Answer: Option (b) is the correct answer.
Explanation:
A statement which states a scientifically acceptable general principle that is experimentally tested or verified is defined as a theory.
A theory is the sum of a number of observations which are tested in order to get the true result so that a statement can be framed.
Thus, we can conclude that out of the given options, a theory is a well-tested explanation for a broad set of observations.
