Intermolecular forces question: match each of these substances with the property it exhibits.

the substances:
nh3
ch3ch2ch=ch2
ch3(ch2)5ch3
he

the properties:
largest dispersion forces
largest dipole dipole forces
none of the properties listed
the lowest boiling point

NH3 largest dipole dipole forces

CH3CH2CH=CH2 largest dispersion forces

CH3(CH2)5CH3 none of the properties listed

He the lowest boiling point

Explanation:

Here are a few tips that help you eliminate the wrong answers immediately:

NH3 has the largest dipole forces that are so strong that they have their own special name called hydrogen bonding

CH3(CH2)5CH3 has low dispersion forces because it is a branched, not straight, chain

He is a mono-atomic noble gas which means it relies on the weakest of London dispersion forces leading it to have the lowest boiling point

truck y has a greater velocity than truck x.