Number of moles of a substance can be calculated from mass of the substance and its molar mass as follows:
[tex]n=\frac{m}{M}[/tex]
Here, n is number of moles, m is mass and M is molar mass.
For aspirin: 324 mg
Molecular formula is [tex]C_{9}H_{8}O_{4}[/tex] and molar mass of aspirin is 180.157 g/mol, thus, number of moles will be:
[tex]n=\frac{324\times 10^{-3} g}{180.157 g/mol}=0.0018 mol[/tex]
For sodium hydrogen carbonate: 1904 mg
Molecular formula is [tex]NaHCO_{3}[/tex] and molar mass is 84.007 g/mol, thus, number of moles will be:
[tex]n=\frac{1904\times 10^{-3} g}{84.007 g/mol}=0.0226 mol[/tex]
For citric acid: 1000 mg
Molecular formula is [tex]H_{3}C_{6}H_{5}O_{7}[/tex] and molar mass is 192.124 g/mol, thus, number of moles will be:
[tex]n=\frac{1000\times 10^{-3} g}{192.124 g/mol}=0.0052 mol[/tex]
Therefore, number of moles of aspirin, [tex]NaHCO_{3}[/tex] and citric acid in the tablet is 0.0018 mol, 0.0226 mol and 0.0052 mol respectively.
