Which of the hydrocarbons are arranged as per the increasing order of their boiling points?

Explanation:

• In general, the boiling point of hydrocarbons increases with the increasing size and molecular mass (i.e., increasing number of carbon atoms) of the molecule.
• This is because the longer the carbon chain, the stronger the van der Waals forces between the molecules. a greater surface area available for intermolecular attractions, specifically London dispersion forces.

Here's a brief overview of these hydrocarbons:

Propane (C₃H₈) - Three carbon atoms
Butane (C₄H₁₀) - Four carbon atoms
Pentane (C₅H₁₂) - Five carbon atoms
Octane (C₈H₁₈) - Eight carbon atoms
You can see from the number of carbon atoms in each molecule that option 2 is arranged in the correct increasing order of their boiling points, going from the smallest molecule (propane) to the largest (octane).