Answer:
The Curies established that radioactivity is a property of an atom that does not change if changes occur to the physical or chemical properties of the atom.
and
Hans Geiger invented a method for detecting and measuring radioactivity.
Explanation:
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Mass is how much matter is in an object. Volume is how much space an object occupies. Density is the amount of mass in a volume.
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The answer is A. Hope this helps
Explanation:
group 8 elements don't react with other elements because they are noble element which means that they can't lose or gain electron.

Aluminum ions have a charge of +3. This means that the atoms have three more protons than electrons. In order to add electrons to aluminum ions, the purification process therefore requires a large amount of electricity.
Uncharged Aluminum atom must need to lose it's electrons,in order to form the bond with oxygen which has vacant orbitals
ion
atom that has a positive or negative charge because it lost or gained one or more electrons
chemical bond
the attractive force that holds atoms or ions together
ionic bond
a chemical bond in which one atom loses an electron and the other atom gains electrons to form ions
chemical formula
a combination of chemical symbols and numbers to represent a substance
covalent bond
bond formed by the sharing of electrons between atoms
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