Ten original multiple-choice questions and three structured questions with model answers on the Contact and Haber processes, alloys, composites, glass and ceramics, written in SPM style, never copied from past papers.
Try each question before reading the answer. The multiple-choice section trains recall and reasoning; the structured section trains the full written answers that Paper 2 rewards. Every question is original and written in SPM style on the chapter’s content standards.
Part A, Multiple choice
1. Which substance is the catalyst in the conversion of sulfur dioxide to sulfur trioxide in the Contact process? A. Iron B. Platinum C. Vanadium(V) oxide D. Manganese(IV) oxide
Answer: C. The Contact process uses vanadium(V) oxide, V₂O₅; iron is the catalyst in the Haber process.
2. The reaction 2SO₂ + O₂ ⇌ 2SO₃ is exothermic. Why is a temperature of about 450–550 °C used rather than a much lower one? A. To increase the yield of sulfur trioxide B. To give an acceptable rate without lowering the yield too much C. To keep the catalyst solid D. To reduce the pressure needed
Answer: B. A lower temperature gives a higher yield but the rate is too slow, so the temperature is a compromise.
3. Why is the Contact process operated at about 1 atmosphere even though the forward reaction reduces the number of gas moles? A. High pressure would decompose the catalyst B. The yield is already very high at 1 atmosphere C. Sulfur trioxide is a liquid D. Low pressure increases the rate
Answer: B. The yield is already high at atmospheric pressure, so costly high-pressure plant is not justified.
4. In the Contact process, sulfur trioxide is first dissolved in concentrated sulfuric acid rather than water because A. it does not react with water B. dissolving it in water produces a fine acid mist that is hard to condense C. water would neutralise the acid D. it is cheaper
Answer: B. Dissolving SO₃ directly in water forms a dense mist of sulfuric acid, so oleum is made instead.
5. Which equation correctly represents the reaction in the Haber process? A. N₂ + H₂ ⇌ NH₃ B. N₂ + 3H₂ ⇌ 2NH₃ C. N₂ + 2H₂ ⇌ 2NH₃ D. 2N₂ + 3H₂ ⇌ 2NH₃
Answer: B. The balanced equation is N₂ + 3H₂ ⇌ 2NH₃.
6. A high pressure of about 200–300 atmospheres is used in the Haber process mainly to A. speed up the reaction B. increase the yield of ammonia C. lower the temperature needed D. keep the iron catalyst active
Answer: B. The forward reaction has fewer gas moles, so high pressure shifts the equilibrium towards ammonia and raises the yield.
7. A pure metal is soft and easily bent because A. its atoms are held by weak bonds B. its orderly layers of atoms can slide over one another C. it contains impurities D. its atoms are different sizes
Answer: B. In a pure metal the identical atoms form orderly layers that slide when a force is applied.
8. Which alloy is most suitable for making cutlery that must not rust? A. Bronze B. Duralumin C. Stainless steel D. Pewter
Answer: C. Stainless steel contains chromium and nickel, which make it resistant to rusting.
9. Which type of glass is most suitable for laboratory apparatus that is heated strongly? A. Soda-lime glass B. Lead crystal glass C. Borosilicate glass D. Photochromic glass
Answer: C. Borosilicate glass withstands sudden temperature changes without cracking.
10. Ceramics are used as electrical insulators mainly because they A. are cheap B. do not conduct electricity C. are transparent D. are flexible
Answer: B. Ceramics do not conduct electricity, so they prevent current from flowing where it should not.
Part B, Structured questions
Question 1, The Contact process. (a) Name the catalyst used to convert sulfur dioxide to sulfur trioxide. (b) Write the balanced equation for this conversion. (c) The forward reaction is exothermic. Explain why a temperature of about 450–550 °C is chosen rather than a much lower temperature. (d) Explain why the process is carried out at about 1 atmosphere.
Model answer. (a) Vanadium(V) oxide, V₂O₅. (b) 2SO₂ + O₂ ⇌ 2SO₃. (c) A lower temperature would move the equilibrium towards more sulfur trioxide, giving a higher yield, but the rate of reaction would be too slow. A higher temperature speeds up the rate but lowers the yield. The temperature chosen is a compromise that gives a good yield at an acceptable rate. (d) Although the forward reaction reduces the number of gas moles, the yield of sulfur trioxide at about 1 atmosphere is already very high, so building and running high-pressure plant would add cost for very little extra yield.
Question 2, Alloys. (a) State what is meant by an alloy. (b) Using ideas about the arrangement of atoms, explain why an alloy is harder than the pure metal. (c) Name one alloy and state one use, giving the property that makes it suitable.
Model answer. (a) An alloy is a mixture of two or more elements, of which the main one is a metal. (b) In a pure metal the atoms are the same size and arranged in orderly layers that can slide over one another, so it is soft. In an alloy, foreign atoms of a different size disrupt the orderly arrangement and prevent the layers from sliding, so the alloy is harder. (c) Stainless steel is used for cutlery because it resists rusting. (Duralumin for aircraft bodies because it is light and strong is also acceptable.)
Question 3, Materials and their uses. (a) State what is meant by a composite material. (b) Explain why reinforced concrete is used for the beams of a building rather than plain concrete. (c) Give one property of ceramics and state a use that depends on that property.
Model answer. (a) A composite material is made by combining two or more materials so that the product has better properties than the individual components. (b) Plain concrete is strong under compression but weak and cracks under tension; steel bars are strong under tension. The composite is strong under both forces, so the beams can carry heavy loads without cracking. (c) Ceramics have a very high melting point, so they are used as furnace linings; or ceramics do not conduct electricity, so they are used as electrical insulators.
How to mark yourself
For the structured questions, award yourself the mark only where your answer names both sides of a compromise or links a property to a use. If you wrote only “to speed up the reaction” in Question 1(c), that is a half-answer. Rewrite it until it names the effect on rate and the effect on yield. A one-to-one teacher can mark a full set of your answers and show you exactly which phrases the SPM Chemistry scheme is looking for, then set you more of the same until the reasoning is secure.
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