After two half life it must be 1200 x 1/2 x 1/2 = 300 atoms.
It doesn't.
All of the actinides are radioactive, and almost all are synthetic.
A radioactive rock is one which contains traces of radioactive isotopes. These isotopes release radiation in its various forms. Any rock can be radioactive, but in particular igneous rocks tend to have radioactive properties. This is because they may have radon gas trapped in their crystals, which, under pressure, is released (this is why radon gas is used as an indicator of an upcoming earthquake). Radon gas is radioactive, and this causes the rock to be radioactive also.
Group 3 of the periodic table contains many of the radioactive elements.
yes, off the top of my head i can think of carbon 14, which is radioactive and has a half life of 5370 years.
The most familiar of the radioactive minerals is pitchblende which contains uranium.
true
It doesn't.
All of the actinides are radioactive, and almost all are synthetic.
Salt substitute - contains potassium chloride. A slight amount of naturally occuring potassium is radioactive.
an unstable, radioactive isotope that contains too many protons
A radioactive rock is one which contains traces of radioactive isotopes. These isotopes release radiation in its various forms. Any rock can be radioactive, but in particular igneous rocks tend to have radioactive properties. This is because they may have radon gas trapped in their crystals, which, under pressure, is released (this is why radon gas is used as an indicator of an upcoming earthquake). Radon gas is radioactive, and this causes the rock to be radioactive also.
Radioactive Contamination
Any of a variety of elements might do for this, including thorium and uranium, but even potassium has an important radioactive isotope in it.
Group 3 of the periodic table contains many of the radioactive elements.
False. All matter, including living matter, contains traces of radioactive isotopes.
It contains a higher amount of radioactivity