Radium is usually found in compounds. Since it is an alkaline earth metal it is to reactive to exist in its elemental states in most environments, and especially in Earth's oxidizing atmosphere.
It is a compound
Calcium is never found in its elemental form in nature.
In nature, titanium is always found as a compound, not as a pure metal. Titanium is highly reactive (although less reactive alloys can be made from it).
pure form
Gold is used usually in pure form or as an alloy.
It is a compound
In pure form.
helium doesn't form any compound
Usually it is found in compound form but can easily as a pure element, just depends on the conditions
Radium is a radio active element which always undergoes nuclear fission and desentegration, and releases energy in the form of radiation. It is an element. There is no compound in it. It contains atoms of radium.
As radium is radioactive, radium chloride would also be radioactive. Any compounds make with any radioactive material are radioactive, and they cannot be "not" radioactive. Radioactive material doesn't really care if it is "alone" or in compound; it will be radioactive in any case.
Calcium is never found in its elemental form in nature.
No plural for radium.
In nature, titanium is always found as a compound, not as a pure metal. Titanium is highly reactive (although less reactive alloys can be made from it).
When radium-226 decays to form radon-222, the radium nucleus emits a alpha particle.
pure form
No. CO2 is carbon dioxide, which is a compound of carbon and oxygen. It is usually formed by a reaction between oxygen and carbon or a carbon contain compound. Oxygen is a single element which is usually found in the form of O2.