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You can post any questions regarding the answers but please do not ask me how many marks to secure an A for the examination. Nobody will know so there is no point in discussing this.

14 Comments

  • Claire

    Hi thank you so much for uploading the answers! 🙂 May I know why is qn 8 answer A? It makes sense but what’s the exact concept?

    • Mr Eric Lee

      The reason for propane to be liquefied is because under high pressure, the propane molecules are so close together that they can only slide past each other in a disorderly arrangement. Hence, they form a liquid state. This is because propane has more carbon and hydrogen atoms and this is explained by a higher molecular mass as given in Option A.

      While Option C seems to answer the question also because more electrons means stronger van der Waals’ forces of attraction, under the high pressure of liquefying propane, the volume of the molecules play a more significant role as compared to the magnitude of the intermolecular forces.

      I would think that the size of the molecule is more important and it will better answer the question of why propane can be liquefied more easily.

    • Mr Eric Lee

      The reason for propane to be liquefied is because under high pressure, the propane molecules are so close together that they can only slide past each other in a disorderly arrangement. Hence, they form a liquid state. This is because propane has more carbon and hydrogen atoms and this is explained by a higher molecular mass as given in Option A.

      While Option C seems to answer the question also because more electrons means stronger van der Waals’ forces of attraction, under the high pressure of liquefying propane, the volume of the molecules play a more significant role as compared to the magnitude of the intermolecular forces.

      I would think that the size of the molecule is more important and it will better answer the question of why propane can be liquefied more easily.

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