Tetraoxosulphate (VI) acid is considered as a heavy chemical because

Analyze the question: It asks why sulphuric acid (H₂SO₄, tetraoxosulphate(VI) acid) is classed as a "heavy chemical."

Explain the concept: In industrial chemistry, "heavy chemicals" are not defined by molecular mass or weight. They are chemicals produced in very large quantities (thousands to millions of tonnes per year) by industry. Examples include sulphuric acid, sodium hydroxide, sodium carbonate, ammonia, and nitric acid. They are usually cheap, impure or bulk-grade, and serve as raw materials for making other products. "Fine chemicals," by contrast, are made in small quantities and are highly pure, such as pharmaceuticals.

Solution (checking each option):

• A. Its relative molecular mass is high. False. H₂SO₄ has a molar mass of 98 g/mol, which is not especially high, and molecular mass is not the criterion anyway.
• B. A high tonnage is produced every year. True. Sulphuric acid is among the most widely produced industrial chemicals in the world, used in fertilizers (superphosphate), detergents, paints, batteries, and more.
• C. It is an inorganic chemical. Being inorganic does not make a chemical "heavy." Many inorganic chemicals are made in small amounts.
• D. It is used to manufacture heavy chemicals. Not the defining reason. Heavy chemicals are defined by the scale of their own production.

Tip: "Heavy" in "heavy chemicals" refers to tonnage (quantity produced), not weight or molecular mass. Whenever you see "heavy chemical" in WASSCE, JAMB, or NECO, think large-scale production.