Question

part a
which element is a molecular element?
krypton
sodium
copper
chlorine

Explanation:

To determine the molecular element, we analyze each option:

• Krypton (Kr) is a noble gas, existing as single atoms (monatomic).
• Sodium (Na) is a metal, existing as individual atoms in a metallic lattice.
• Copper (Cu) is a metal, existing as individual atoms in a metallic lattice.
• Chlorine (Cl) is a non - metal from Group 17 (halogens). Halogens exist as diatomic molecules ($Cl_2$) in their elemental form, so it is a molecular element.

Answer:

D. chlorine