Question

which element is a noble gas? *
2 points
periods
groups
carbon (c)
krypton (kr)
barium (ba)
magnesium (mg)

Explanation:

Noble gases are in Group 18 of the periodic table. Carbon (C) is in Group 14, Barium (Ba) is in Group 2, Magnesium (Mg) is in Group 2. Krypton (Kr) is in Group 18, so it is a noble gas.

Answer:

Krypton (Kr)