Final answer:
H₂SO₃ is named sulfurous acid, as it forms the sulfite ion when dissolved in water.
Step-by-step explanation:
The name of H₂SO₃ is sulfurous acid. When naming acids, if the acid is composed of hydrogen, sulfur, and oxygen, the acid’s name is based on the anion it forms when dissociated in water.
Since the anion formed is the sulfite ion (SO₃²⁻), the corresponding acid is sulfurous acid. This is in contrast to sulfuric acid, which correlates to the sulfate ion (SO₄²⁻). Sulfurous acid is known to be a moderately strong, unstable acid that ionizes in two steps to form the hydrogen sulfite ion (HSO₃⁻) and the sulfite ion (SO₃²⁻).