1. given the following full electron configuration, which is the noble gas electron configuration? → 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2
a. [ar] 4s^2
b. [mg] 3p^6 4s^2
c. [ne] 3s^2 3p^6 4s^2
d. [ne] 4s^2
( i am so lost)

The element identified in the original electron configuration is Calcium, Ca, so move backwards from there. The noble gas you reach first is Argon. For the noble gas configuration, you'd use Argon and then 4s^2 to acknowledge that it's still Calcium that the electron configuration is identifying.

The answer is A, [Ar] 4s^2.

Let me know if you need more of an explanation on electron configuration itself.

a chemical reaction

explanation:

the correct option is c.

isotopes refers to different forms of the same element with the same atomic number but different mass number as a result of difference in their neutron numbers. isotopes have different relative atomic mass but share the same chemical properties.