a) True
b) False

Answer: a
Explanation: The given statement is true. Several pulping processes are based on the use of sulfur dioxide as the essential component of the pulping liquor. Sulfur dioxide dissolves in water to form sulfurous acid, and a part of the acid is neutralized by a base during preparation of the pulping liquor. The various sulfite processes differ in the kind of base used and in the amount of base added. These differences govern the resulting acidity or pH of the liquor. These processes depend on the ability of sulfite solutions to render lignin partially soluble.