Explanation:

- Sulphurous acid has the chemical formula H2SO3.

- Calculate the molecular mass:

- Hydrogen (H): 2 atoms × 1.01 amu = 2.02 amu

- Sulfur (S): 1 atom × 32.07 amu = 32.07 amu

- Oxygen (O): 3 atoms × 16.00 amu = 48.00 amu

- Total molecular mass = 2.02 + 32.07 + 48.00 = 82.09 amu

- Option 1: 96.04 - This is incorrect; it's closer to the mass of H2SO4 (sulfuric acid).

- Option 2: 98.07 - This is incorrect as it's not relevant to H2SO3.

- Option 3: 87.06 - This is incorrect, being too high for H2SO3.

- Option 4: 82.07 - This is the closest correct option for H2SO3.