<span>Platinum is solid at room temperature. SInce the catalyst is solid while the medium involves gases, this catalyst is characterized as heterogenous. Because they are different states of matter, they can be easily separated through physical means. So, the answer is B.</span>
<span>rusting takes a long time, and rusting is a chemical change.</span>
#1...Evaporation
#2....Gas
The classification of it being a metal, nonmetal, or metalliod will be useful in the process of elimination to determine what it is. Then for the second test, meauring the atomin radius will narrow it down quicker to the mystery elemet's name.
Since you determined what part of the periodic table it's on, then when measuring the atomic radius, you should be able to pinpoint what the element is more surely.
Answer:
Pretty sure the answer is B
