Answer:
An Element
Explanation:
An Element is made up of only one type of atom (Gold, Silver, etc.)
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Science is how we make sense of the world by collecting data and doing experiments. Scientific ideas change over time as our evidence improves. The more experiments we do and the more data we collect, the better our scientific ideas become.
Answer:
The atomic radius of a chemical element is a measure of the size of its atoms, usually the mean or typical distance from the center of the nucleus to the boundary of the surrounding shells of electrons.
Answer:
The Avogadro's number is 
Explanation:
From the question we are told that
The edge length is 
The density of the metal is 
The molar mass of Ba is 
Generally the volume of a unit cell is

substituting value
![V = [5.02 *10^{-10}]^3](https://tex.z-dn.net/?f=V%20%3D%20%20%5B5.02%20%2A10%5E%7B-10%7D%5D%5E3)
From the question we are told that 68% of the unit cell is occupied by Ba atoms and that the structure is a metal which implies that the crystalline structure will be (BCC),
The volume of barium atom is

substituting value


The Molar mass of barium is mathematically represented as

Where
is the Avogadro's number
So

substituting value

