The attractions that allow molecules of krypton to exist in the solid phase are due to:
1) ionic bonds
2) covalent bonds
3) molecule-ion forces
4) van der waals forces

4) Van der waals forces

Explanation:

Krypton (Kr) belongs to the noble gas group and has fully filled valence orbitals. In the solid phase, Kr exists as a white solid with a face centered cubic structure.

Intermolecular forces of attraction from the strongest to the weakest include:

Ionic > hydrogen bonding > dipole-dipole > london dispersion

Kr is monoatomic and non-polar. When fully filled (stable) valence orbitals of 2 Kr atoms approach each other in close proximity they experience a repulsive force which prevents the formation of strong bonds. Thus, the only force of attraction in Kr is the long range weak Van Der Waals force also known as the london dispersion force.