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To determine the fraction of the hydrogen atom's mass that is in the nucleus, we have to keep in mind that
a Hydrogen atom has 1 proton and 1 electron.
Protons are in the nucleus while electrons are in electron shells surrounding the nucleus.
The mass of the nucleus will be equal to the mass of 1 proton and we can express the fraction as follows:

So, the fraction of the hydrogen atom's mass that is in the nucleus is
0,9995. That means that almost all the mass of this atom is at the nucleus.
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Answer:
The empirical formula of the solid metal oxide is : 
Explanation:
M atom is present in the every corner and in the center of every face.
Number of m atoms :

Number of tetrahedral voids in F.C.C = 2n = 2 × 4 = 8
Oxide ion is present in the half of the tetrahedral void
Number oxide ions = 
The molecular formula of the solid metal oxide is : 
The empirical formula represent the lowest number of atoms present in a compound.
The empirical formula of the solid metal oxide is : 
Answer:
Explanation:
Percent composition is percentage by the mass of element present in the compound.
The formula for chromium(III) nitrate is 
Molar mass of chromium(III) nitrate = 238.011 g/mol
1 mole of chromium(III) nitrate contains 9 moles of oxygen
Molar mass of oxygen = 16 g/mol
So, Mass= Molar mass*Moles = 16*9 g = 144 g