Which particle has the same electron configuration as a potassium ion?

A. fluoride ion

B. sodium ion

C. neon atom

D. argon atom

Answer is D - Argon atom

Potassium has atomic number as 19. Hence, number of protons = 19

If the atom is neutral,

number of protons = number of electrons = 19

Hence, the electron configuration of potassium (K) is

1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹

Potassium ion is formed by losing an electron. Then the number of electrons = 19 - 1 = 18

Electron configuration of K⁺ is 1s² 2s² 2p⁶ 3s² 3p⁶.

This is same as the electron configuration of Ar which has 18 electrons.

Argon atom has the same electrons configuration as a potassium ion.