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

The boiling point of hydrocarbons, specifically alkanes, is directly proportional to the molecular mass and the length of the carbon chain. As the number of carbon atoms increases, the surface area of the molecule increases, leading to stronger Van der Waals forces (intermolecular attractions). Consequently, more thermal energy is required to overcome these forces and transition the substance into a gaseous state.

In Option B, the hydrocarbons are arranged as follows:

• Propane: 3 Carbon atoms (C3H8)
• Butane: 4 Carbon atoms (C4H10)
• Pentane: 5 Carbon atoms (C5H12)
• Octane: 8 Carbon atoms (C8H18)

Since the number of carbon atoms increases progressively (3 < 4 < 5 < 8), this sequence correctly represents the increasing order of boiling points. Other options are incorrect as they do not follow a consistent ascending order of carbon chain length.