Answer:
2-
Explanation:
For an element to be stable, it must follow the octet rule: an atom will gain, lose or share electrons until its valence shell is complete with 8 electrons.
An element with the valence electron configuration ns²np⁴ has 6 (2+4) electrons in its valence shell. Thus, in order to fulfill the octet, it will gain 2 electrons. As a consequence, it will form an anion with charge 2-.
Naturally Occurring Radioactive Materials (also known as NORM) are a wide range of radioactive isotopes that include elements such as carbon 14 and potassium 40, both of which are in the human body. But the main radioactive elements involved in oil and gas production are those found throughout Earth's crust. These elements include uranium and thorium and their respective byproducts, including radon gas.
The majority of the mass of the atom is located in the nucleus. Remember that the nucleus contains both protons and neutrons and therefore, most of the mass of the atom.
