a. Number of molecules=Avogradro's contant⋅Number of moles
0.45(6.02⋅1023)=2.709⋅1023≈2.71⋅1023
b. Number of atoms=Number of molecules⋅Number of atoms in one molecule
NH4Cl = 6 atoms
6(2.709⋅1023)=1.6254⋅1024≈1.63⋅1024
c. Number of atoms in 1 mole=Avogadro's constant⋅Number of atoms in one molecule
6(6.02⋅1023)=3.612⋅1024≈3.61⋅1024
d. Number of atoms of one element=Number of molecules⋅Number of atoms of one element in one molecule
4(2.709⋅1023)=1.0836⋅1024≈1.08⋅1024
d. n(NH4Cl)=0.45mol
n(H4) in NH4Cl=0.45⋅453.5=0.0336448598≈3.36⋅10−2mol