Which of the following raw materials is used in the plastic industry?

Step 1: Analyze the question The question asks which substance is a raw material for making plastics. Plastics are polymers, which are long chains built from small repeating units called monomers.

Step 2: Explain the concept Many common plastics are made by addition polymerization of alkenes. Ethene (C₂H₄) has a carbon-carbon double bond. This bond opens up so that many ethene molecules can join together:

n CH₂=CH₂ → (–CH₂–CH₂–)ₙ Ethene → Polyethene (polythene)

Polythene is used for sachets ("pure water" nylons), bags, bowls, and buckets, all of which are very familiar in Nigeria.

Step 3: Check each option

• A. Ethene: It is the monomer for polythene. Yes, it is a raw material for plastics.
• B. Methane: This is mainly used as fuel (natural gas) and to make hydrogen and methanol. It is not a direct monomer for plastics.
• C. Sulphur: It is used to make sulphuric acid and to vulcanize rubber. It is not a plastic raw material.
• D. Hydrogen: It is used in the Haber process for ammonia and in the hydrogenation of oils to make margarine. It is not a plastic raw material.

Step 4: Answer The correct option is A. Ethene.

Exam tip: Remember "Alkenes make plastics." Ethene gives polythene, propene gives polypropylene, and chloroethene (vinyl chloride) gives PVC. If you see "plastic" or "polymer" in a question, look for an alkene or an unsaturated monomer first.