Noble gas molecules are held together by

Step 1: Analyze the question The question asks which force holds noble gas particles together. Noble gases are helium, neon, argon, krypton, xenon and radon.

Step 2: Explain the concept Noble gases have complete outer electron shells (2 electrons for helium, 8 for the others). Because of this:

• They do not readily lose, gain, or share electrons.
• They exist as single atoms (monatomic), not as bonded molecules.

So they cannot form ionic, covalent or dative bonds under normal conditions. Hydrogen bonding needs hydrogen attached to a very electronegative atom (N, O or F), which noble gases don't have.

The only attraction between noble gas atoms is the weak van der Waals forces, also called London dispersion forces. These arise from temporary, instantaneous dipoles. The electron cloud shifts momentarily, creating a slight charge imbalance that induces a dipole in a neighbouring atom.

Step 3: Check each option

• A. van der Waals forces: Correct. They are the only forces between noble gas atoms, which is why noble gases have very low melting and boiling points.
• B. Hydrogen bonds: Incorrect. No hydrogen is bonded to N, O or F.
• C. Dative bonds: Incorrect. These need a lone pair donated to an electron-deficient atom, and noble gases don't do this normally.
• D. Covalent bonds: Incorrect. Their shells are already full, so they have no need to share electrons.

Step 4: Answer The correct option is A, van der Waals forces.

Tip: Remember "Noble = no bonding, only weak van der Waals." Boiling points of noble gases rise down the group (He → Rn) because larger atoms have more electrons, so the van der Waals forces are stronger.