Question

the name of the noble gas in period 3 is ______.
○helium
○neon
○krypton
○argon

Explanation:

Noble gases are in group 18 of the periodic table. Period 3 elements are in the third row. Helium is in period 1, neon in period 2, krypton in period 4, and argon is in period 3 (atomic number 18, electron configuration ends in a full valence shell, characteristic of noble gases).

Answer:

D. argon