
<em>Chemists use the mole unit to represent 6.022 × 10 23 things, whether the things are atoms of elements or molecules of compounds. This number, called Avogadro's number, is important because this number of atoms or molecules has the same mass in grams as one atom or molecule has in atomic mass units. </em>
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The ion N³⁻ is called the azide ion. In its neutral state, it occurs as the element Nitrogen. The atomic number of Nitrogen is 7. When it turns into an anion (negatively charged ion), it gains 3 more electrons. That's why its net charge becomes -3. It means that the protons is still 7, but the electrons are now 10.
Overall charge = +7 + -10 = -3
Answer: made up of an infinite number of indestructible atoms in unpredictable motion.
has 37 electrons in the orbit about its nucleus.
<h3>How to write an atomic symbol with atomic mass and atomic number?</h3>
Atomic mass is the total number of neutrons and protons present in the nucleus of an element.
The atomic number is the total number of protons present in the nucleus of an element.
For writing an atomic symbol, atomic mass is written on the top left of the atomic symbol, and the atomic number is written on the downside of the left of the symbol.

An electrically neutral atom is an atom that has an equal number of electrons as well as protons.
Thus from the above conclusion we can say that
has 37 electrons.
Learn more about Atomic mass and atomic number here:
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Oxidation state of Pb in PbO2 is +4.
Oxidation state of Pb in PbCl2 is +2.
Oxidation state of Pb in Pb2O is +1.
Oxidation state of Pb in Pb4O3 is +6/4.
Hence option A. PbO2 is correct.
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