Identify the types of interactions

We need the decreasing order of strength among:

• ion-ion
• ion-dipole
• dipole-dipole

Recall the general trend

The strength of electrostatic interaction depends on the magnitude of charges involved.

• Ion-ion: attraction between full charges, e.g. $\text{Na}^+$ and $\text{Cl}^-$
• Ion-dipole: attraction between a full charge and a partial charge, e.g. $\text{Na}^+$ with water
• Dipole-dipole: attraction between partial charges of polar molecules

Since a full charge-full charge interaction is strongest, then full charge-partial charge, and finally partial charge-partial charge is weakest.

Therefore, decreasing order is

$\text{ion-ion} > \text{ion-dipole} > \text{dipole-dipole}$

Check the options

• A: $\text{dipole-dipole} > \text{ion-dipole} > \text{ion-ion}$ ❌ reversed
• B: $\text{ion-dipole} > \text{dipole-dipole} > \text{ion-ion}$ ❌ ion-ion should be strongest
• C: $\text{ion-dipole} > \text{ion-ion} > \text{dipole-dipole}$ ❌ ion-ion should be stronger than ion-dipole
• D: $\text{ion-ion} > \text{ion-dipole} > \text{dipole-dipole}$ ✅ correct

Final Answer

$\boxed{\text{ion-ion} > \text{ion-dipole} > \text{dipole-dipole}}$

Hence, the correct option is D.