Question

A particular element has the following set of properties:

• It has a low melting point.
• It has a low boiling point
• It exists as a two-atom molecule in the gas phase.
It has seven outer electrons.
• It readily reacts with metals to produce a salt.
Which element does the list describe?
A.
iodine (1)
B. hydrogen (H)
C. xenon (Xe)
D.
barium (Ba)

Answer 1

A. Iodine

Step-by-step 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.