Element
Cobalt, the transition metal, is an element. It's element number 27, and it does not occur naturally as an element or as a mixture, but rather as a compound. Links are provided.
Astatine is an element that does not occur naturally in large quantities on Earth.
As a compound
An element occur in nature as a pure element or as a compound.
boron
Copper occurs naturally as both an element and in various compounds. In its pure form, copper is an element on the periodic table with the symbol Cu. However, it can also be found in nature as compounds such as copper oxide and copper sulfide.
Heating iodine sublimation occur: this is a direct change from solid to gas.
Halogens naturally occur in the gaseous state. Examples of halogens are fluorine, chlorine, bromine, iodine, and astatine.
Dry ice is not an element. Dry ice is solid carbon dioxide, CO2, which is a compound.
everywhere. when there are trees in that area
Iodine naturally occurs in the earth's soil, seawater, and some types of rock. It is also found in certain foods such as seafood, dairy products, and grains, as well as in some plants grown in iodine-rich soil.
Nobelium is an artificial element.