Which of the following substances can be classified as heavy chemicals?

Analyze the question: "Heavy chemicals" is an industrial term. It refers to chemicals produced in very large quantities (thousands of tonnes) as bulk raw materials for many other industries. They are not defined by their atomic weight.

Concept: Typical heavy chemicals include:

• Sulphuric acid (H₂SO₄)
• Sodium hydroxide (NaOH)
• Sodium carbonate (Na₂CO₃)
• Nitric acid (HNO₃)
• Ammonia (NH₃)
• Hydrochloric acid (HCl)

Sulphuric acid is the standard example. It is called the "king of chemicals" because it is used in fertilizers, detergents, paints, batteries, and many other products.

Checking the options:

• A. CaOCl₂ (bleaching powder): Made in smaller quantities and used mainly for bleaching and disinfecting. It is not a typical heavy chemical.
• B. H₂SO₄ (sulphuric acid): Produced in massive quantities as an industrial raw material. It is a heavy chemical.
• C. AgNO₃ (silver nitrate): Used in small amounts, for example in photography and laboratory analysis. It is a fine chemical, not a heavy chemical.
• D. CaO (quicklime): It is a bulk industrial material, but it is usually classed as a basic material or construction material, not a classic heavy chemical. The standard textbook answer is H₂SO₄.

Answer: B. H₂SO₄.

Exam tip: When you see "heavy chemicals" in WASSCE, JAMB or NECO, think of the big industrial acids, alkalis and salts, led by H₂SO₄, NaOH and Na₂CO₃. Chemicals used in small quantities for specialised purposes, like AgNO₃, are "fine chemicals."