Answer:
8 to 8.5 since that is the recommended and people usualy sleep more than that
Oxygen,carbon,hydrogen,and nitrogen- together make up 95 percent of the mass of the human body.
Hope this helps.
The purpose is that it shows you all the elements we know and it arranges them in groups that are also the same kind like Chemistry.
I think it’s C but not certainly positive
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Answer: five cause </h3>
The number of energy levels of zirconium is 5, and I know this because it is located in family five. Families are the rows across on the periodic table. The family number is always equal to the number of energy levels.Zirconium: properties of free atoms. Zirconium atoms have 40 electrons and the shell structure is 2.8.
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Explanation: