Atom is the
most basic unit of matter. They are the general term used to describe pieces of
matter. But a different kind of atom makes up an element. A combination of atom of different elements
creates a molecule. For example, you have water; it has a chemical formula of
H2O. If you separate H from O, you have two atoms. Two atoms for hydrogen and
one atom for oxygen. However, they are of different elements. And when you
combine them to form H2O, you create a molecule.
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Answer:
The number of electrons in a neutral atom is equal to the number of protons. The mass number of the atom (M) is equal to the sum of the number of protons and neutrons in the nucleus. The number of neutrons is equal to the difference between the mass number of the atom (M) and the atomic number (Z).
Explanation:
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Answer:
1) 40
2) 2.25 moles
3) 17
4) 120
5) Fe₂O₃
Explanation:
Please see attached picture for full solution.
From the calculations, the half life of the material is 6.5 days.
<h3>What is radioactivity?</h3>
The term radioactivity has to do with the spontaneous disintegration of a specie.
Uisng the formula;
N=Noe^-kt
N= amount at time t = 0.135 Ci or 4.995 ×10^9 Bq
No = amount initially present = 1.75 x 10^12 Bq
k = rate constant = ?
t = time taken = 55 days
Hence;
4.995 ×10^9 = 1.75 x 10^12e^-55k
4.995 ×10^9/1.75 x 10^12 = e^-55k
2.85 * 10^-3 = e^-55k
ln2.85 * 10^-3 = -55k
k = ln2.85 * 10^-3/-55
k = 0.1066 day-1
Half life = 0.693/ 0.1066 day-1
= 6.5 days
Learn more about radioactivity:brainly.com/question/1770619
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