Homework

what is the volatility of the halogent ive forgotten

Miisssss

I would expect that you may not read this until tomorrow but lets hope... basically i think I was going down the wrong road when writing my conclusion, which is why I am lacking in a completed one. I understand the enthalpy decreases as the length of the hydrocarbon increases, and at first I thought "they have weaker intermolucular forces"
Am I right, an If so why do they have weaker forces? And If I am wrong, what is the answer? Google has not been very helpful!
I hope you find this before the end of the evening as I may not be able to finish otherwise, and I really don't want you to shout at me :(
Sorry
Anyone who can help please do x