Final answer:
Heavier hydrocarbons will turn into solids at surface conditions because their intermolecular forces are strong enough to hold the molecules in a fixed position, resulting in a substance with a soft, waxy consistency. (option b)
Step-by-step explanation:
The question concerns what would happen to heavier hydrocarbons at surface conditions. Among the given options, the correct answer is that they will turn into solids. This is because, as per the information provided, small hydrocarbons like methane and ethane are gases at room temperature, while larger ones such as hexane and octane are liquids.
Even larger hydrocarbons are solids at room temperature and tend to have a soft, waxy consistency. Therefore, at surface conditions, which assume a general Earth-like environment with pressures around 1 atm and temperatures around 20°C, the heavier hydrocarbons would not evaporate into gases, remain in liquid form, or transform into light hydrocarbons; they would solidify due to the intermolecular forces being strong enough to hold the molecules in a fixed position.
Hence, the answer is option b