Question

Two alkanes 'A' and 'B' have 3 and 5 Carbon atoms in their molecules, respectively. In which physical state will they occur at room temperature?

Answer 1

• The melting and boiling temperatures of Hydrocarbons in a homologous series rise as the molecular mass rises.
• As a result, a molecule with a greater number of Carbon atoms will have higher melting and boiling temperatures.
• Hydrocarbons with fewer Carbon atoms have lower melting and boiling points.
• Hydrocarbons with fewer Carbon atoms are gases, hydrocarbons with more Carbon atoms are solids, and hydrocarbons with an intermediate quantity of Carbon atoms are liquids.
• Therefore, generally Hydrocarbons with 1 to 4 carbon atoms are gases, those with 5 to 13 carbon atoms are liquids, and those with more than 14 Carbon atoms are solids.

So, ‘A’ is in a gas state and ‘B’ is in a liquid state.