Answer:
A. Iodine
Explanation:
First 2 points describe it's physical properties. Even if we don't remember them, we can easily figure out the answer to be a non-metal. As, non-metals usually have lower bp and mp than metals.
Both Iodine and hydrogen exists as a 2 atom molecule in gas phase.
But only elements of group 17 (halogens) have 7 electrons in their outer shell.
Again, salts are usually ionic compounds, formed by atoms with a greater difference in their electronegativities. Hence, the one that forms bonds with a metal to form a salt readily can be a non- metal.
All these points indicate that the element must be iodine.
