Choose the correct statements.
a. the noble gases are very unstable.
b. in the world, elements are usually in their pure form.
c. eight electrons in the outer shell is the most stable configuration.
d. a chemical bond is a strong attractive force between atoms.

The correct answer to your question is:  C

Explanation:

A. The noble gases are very unstable.  This option is wrong because noble gases are the most stable elements.

B. In the world, elements are usually in their pure form.  this option is wrong because most of the elements are part of compounds.

C. Eight electrons in the outer shell is the most stable configuration.  This option is correct, metals and non metals reach stability by gaining or losing electrons to reach electrons

D. A chemical bond is a strong attractive force between atoms. This option is also right, this is a correct definition of chemical bond.

it is the most commonly accepted one