Which element will have a noble gas configuration if it forms an ionic bond by donating one electron to a fluorine atom?
A.
chlorine (Cl)
B.
sulfur (S)
C.
calcium (Ca)
D.
potassium (K)

Potassium (K) having 9 valance electrons can donate a single electron to Fluorine and reach the noble state by completing the Octet.

Option D

Explanation:

Octet Rule:

When the atoms of an element hold 8 independent valance electrons in their outermost orbit; the element converts into its noble state where it doesn't need to react or combine to any other element and gets stable. Each element tend to reach such state by either donating or receiving electrons to satisfy the Octet rule.

Here in this case, we can see that its Potassium which can donate a single electron to Fluorine as it has 19 electrons in each of its atoms. If we see its electronic configuration, we will know that the electrons are divided in three orbits having 2, 8 and 9 electrons, respectively.

Now, if a Potassium atom leaves one of its valence electrons out of 9; the count will be reduced to 8 which will make it stable according to the Octet Rule and hence, it forms a noble gas. Thus, it's Potassium which can donate an electron and gets stable.