<u>Answer:</u>
<u>For a:</u> The number of sodium ions in given amount of sodium sulfite are 
<u>For b:</u> The number of sulfite ions in given amount of sodium sulfite are 
<u>For c:</u> The mass of one formula unit of sodium ions is
grams
<u>Explanation:</u>
The chemical formula of sodium sulfite is
. It is formed by the combination of 2 sodium
ions and 1 sulfite
ions
To calculate the number of moles, we use the equation:

Given mass of sodium sulfite = 2.80 g
Molar mass of sodium sulfite = 126 g/mol
Putting values in above equation, we get:

Moles of sodium ions in sodium sulfite = (2 × 0.022) moles
According to mole concept:
1 mole of a compound contains
number of particles
So, 0.022 moles of sodium sulfite will contain =
number of sodium ions
Hence, the number of sodium ions in given amount of sodium sulfite are 
Moles of sulfite ions in sodium sulfite = (1 × 0.022) moles
According to mole concept:
1 mole of a compound contains
number of particles
So, 0.022 moles of sodium sulfite will contain =
number of sulfite ions
Hence, the number of sulfite ions in given amount of sodium sulfite are 
Molar mass of sodium sulfite = 126 g/mol
According to mole concept:
number of formula units are present in 1 mole of a compound
Or,
number of formula units of sodium sulfite have a mass of 126 grams
So, 1 formula unit of sodium sulfite will have a mass of = 
Hence, the mass of one formula unit of sodium ions is
grams