Multiple choice

Find the odd one out.

Sodium (Z = 11); Aluminium (Z = 13); Chlorine (Z = 17); Argon (Z = 18); Potassium (Z = 19)

  1. Aluminium

  2. Argon

  3. Chlorine

  4. Potassium

  5. Sodium

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Potassium belongs to the fourth period whereas the remaining elements belong to the third period.