Place the compounds in order from weakest IMFs to strongest IMFs from the lists below.?

The answer: 1) H₂S, NH₃, CCl₄

NH₃ molecules are held together by hydrogen bonds, while H₂S and CCl₄ molecules are held together by van der Waals' forces.

For molecules with similar sizes, hydrogen bonds are stronger than van der Waals' forces. As H₂S and NH₃ have similar molecular sizes, the hydrogen bonds in NH₃ is stronger than the van der Waals' forces in H₂S.

The larger the molecular size, the stronger the van der Waals' forces are. As CCl₄ molecule is much larger in size than NH₃ molecule, the van der Waals' forces in CCl₄ is stronger than the hydrogen bonds in NH₃.

Evidence :
Boiling points : H₂S (-60°C) < NH₃ (-33°C) < CCl₄ (77°C)

Intermolecular forces.....

When it comes to forces and bonds between molecules we have hydrogen bonding and the three van der Waals forces, which are Keesom forces (dipole-dipole attraction), Debye forces (induced attractions) and London dispersion forces (which are present between all molecules). Contrary to what often appears in some out-dated textbooks and some teachers' dusty old notes, London dispersion forces are not the weakest of the three van der Waals forces, and are often second only to hydrogen bonding in strength.

H2S .... Polar molecule (u = 0.97D). London dispersion forces, Keesom forces, Debye forces, weak hydrogen bonding. At room temperature H2S is a gas. (BP = -60C)
NH3 .... Polar molecule (u = 1.46D). London dispersion forces, Keesom forces, Debye forces, strong hydrogen bonding. At room temperature NH3 is a gas. (BP = -33C)
CCl4 .... Nonpolar molecule (u = 0). London dispersion forces only. At room temperature CCl4 is a liquid. (BP = 77C)

Here is the perfect example of how London dispersion forces can be the strongest forces on the block.

Weakest ...... Strongest
H2S ..... NH3 ..... CCl4

=========== Follow up ===========

"Size" is not the only factor dealing with the strength of London dispersion forces. The strength of London dispersion forces is based on the polarizability of the molecule, which in turn, depends on the total number of electrons and the area over which they are spread. CCl4 has more electrons along with its greater are means that it is more polarizable, enough so that its boiling point is greater than for either H2S or NH3.