Question

Which of the following elements is a metal?

carbon (C)

iodine (I)

iridium (Ir)

radon (Rn)

Answer 1

Iridium is a metal
Carbon - Graphite, diamonds
Iodine - Non-Metal
Iridium - Conductive Metal
Radon - Radioactive Gas

Answer 2

from the astrophysiscal point of view, everything execpt for hydrogen and helium is called "metal" ;)
but i think it is asked for the actual metal property. so this would be iridium here.

Answer 3

Iridium is the only metal in this list.

@Marsianer, there is metallic Hydrogen on/in Jupiter

Answer 4

i know^^
but by definition metals are everything bigger than helium for astronomers

Answer 5

How is that definition useful in astronomy

Answer 6

it is because all the hydrogen and most of the helium in the universe is primordial, meaning they were build directly out of the big bang, and all the higher elements were produced in stars.