Question

four different liquid compounds in flasks at 20°c are represented above. the table below identifies the compounds. flask c shows the most particles in the vapor phase. which of the following is not shown in the model but best helps to explain why flask c must contain pentane?

name	chemical formula	boiling point (°c)
hexane	ch₃ch₂ch₂ch₂ch₂ch₃	69
heptane	ch₃ch₂ch₂ch₂ch₂ch₂ch₃	98
octane	ch₃ch₂ch₂ch₂ch₂ch₂ch₂ch₃	126

a the random motion of the particles within the liquids
b the relative speeds of the vapor particles in each flask
c the strength of the intermolecular forces between the particles in the liquids
d the structural formula of the molecules of the liquid and vapor in each flask

Explanation:

Pentane has the lowest boiling - point among the given hydrocarbons. Substances with weaker intermolecular forces have lower boiling - points and are more likely to have more particles in the vapor phase at a given temperature. The strength of intermolecular forces is not shown in the model but best explains why pentane is in flask C (most vapor - phase particles). Random motion of liquid particles and vapor particle speeds do not directly explain the composition of the flask, and the structural formula is given in the table and not the key factor not shown in the model for this explanation.

Answer:

C. The strength of the intermolecular forces between the particles in the liquids