You can cross multiply, it will be easy
2.4 x 10²² atoms
<h3>Further explanation</h3>
Atomic mass is the average atomic mass of all its isotopes
In determining the mass of an atom, as a standard is the mass of 1 carbon-12 atom whose mass is 12 amu
So the atomic mass obtained is the mass of the atom relative to the 12th carbon atom
mass single Uranium atom=4.7 x 10⁻²² g
then for 111 mg=0.111 g

Answer:
barium and silicon has same valence electrons
Explanation:
barium-2,8,18,18,8,2
neon-2,8
silicon-2,8,2,2
carbon-2,4
4.6to the twelth power plus ten or something like that it has been a while since I have done the scientific notation but where ever you put in the number of zeros. is twelve