Another question...

Can you explain this? I don't understand the differences between the interactions.
3. Which of the following is true regarding intermolecular forces?
a. Hydrogen bonds are as strong as covalent bonds
b. On average, dipole-dipole interactions are weaker than induced dipole-induced dipole
c. Induced dipole-induced dipole interactions are stronger for large atoms/molecules
d. Hydrogen bonds occur whenever a molecule contains hydrogen
e. Hydrogen bonds are just a special kind of induced dipole-induced dipole interaction

Let's take these one at a time.
a. Hydrogen bonds are as strong as covalent bonds
Covalent bonds are the bonds that hold molecules together. They are MUCH stronger than any intermolecular force. If IMFs were stronger than covalent bonds, the IMFs would rip molecules apart.
b. On average, dipole-dipole interactions are weaker than induced dipole-induced dipole
Induced dipole-induced dipole interactions (or if you prefer, you can call them London forces, or dispersion forces, or London dispersion forces) are temporary dipoles than change over time. Although some induced dipoles can be very strong and some regular dipoles can be quite weak, an average London force will be weaker than an average dipole-dipole interaction.
c. Induced dipole-induced dipole interactions are stronger for large atoms/molecules
Induced dipoles form when electron clouds are deformed. The bigger an electron cloud, the easier it is to deform. This can be because it's part of a big atom (like I or Po), or because it's part of a big molecule (like long hydrocarbons). The more an electron cloud can deform, the stronger it's induced dipole will be.
d. Hydrogen bonds occur whenever a molecule contains hydrogen
The hydrogen involved in a hydrogen bond has to be polar, that is, it has to be part of a polar bond. A molecule of H₂ contains hydrogen, but the H-H bond is not polar, so we wouldn't call its IMFs hydrogen bonds.
e. Hydrogen bonds are just a special kind of induced dipole-induced dipole interaction
H-bonds are a special/specific type of dipole-dipole interaction.

So it looks like the correct answer is "c".

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