Electrons. Electricity is composed of free electrons and some radioactive decays emit electrons (beta particles)
Hematite itself is not radioactive. It is a common iron oxide mineral that does not exhibit radioactive properties.
Some isotopes are radioactive, some are not.
The most common unit used to express the activity of a radioactive substance is the Becquerel (Bq). One Becquerel is equal to one radioactive decay per second.
anything past bismuth and 2 elements in middle (promethium and another I don't remember). some researchers believe bismuth is also naturally radioactive, but with a half-life longer than the age of the universe.
Not all of the transition elements are radioactive. Many of them are, and some of them have common radioactive isotopes, but some of them have no naturally occurring radioactive isotopes. Please note that all elements have synthetic radioactive isotopes, at least.
Yes, radioactive objects emit heat as a byproduct of their radioactive decay process. This heat is produced by the energy released during the decay of unstable atomic nuclei.
Electrons. Electricity is composed of free electrons and some radioactive decays emit electrons (beta particles)
Some isotopes of xenon do undergo radioactive decay to caesium.
"The radioactive decay of certain unstable isotopes is used to calculate the age of objects."
Mostly no, but it depends on the nature of the two objects. Radioactive objects are usually emitters of alpha particles (helium nuclei), beta particles (electrons), and/or gamma rays (high-energy photons). None of those will usually induce secondary radioactivity in other objects. However, if neutrons are emitted, they can often penetrate the nuclei in another object, and if successfully absorbed there, can produce an unstable (radioactive) isotope. Also, if the source radioactive object is producing radon gas as a decay product, that can also be absorbed by some materials and start generating radiation there. (This does not require that it be "touching".)
Hematite itself is not radioactive. It is a common iron oxide mineral that does not exhibit radioactive properties.
There are not many common nonagonal shapes. Some coins are nonagonal.
It depends on the isotope, of which carbon has three that occur naturally. Carbon-12 (about 99%) and carbon-13 (about 1%) are not radioactive; carbon-14 (trace amounts, maybe one part per trillion) is radioactive (beta decay into nitrogen-14) with a half-life of about 5700 years.
Some isotopes are radioactive, some are not.
Radon is radioactive and is actually a fairly common hazard because of this.
Some common challenges encountered when solving radioactive decay problems include understanding the concept of half-life, calculating decay rates accurately, accounting for different types of decay processes, and dealing with complex decay chains.