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Chemistry Past Questions and Answers

Waec Chemistry Questions

Question 56:

The major raw material in a plastic industry is

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A Ethanol
B Sulphur
C Methylethanoate
D Ethene
E Ethane

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Question 57:

Which of the following reactions represents the laboratory preparation of hydrogen?

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A C_(s) + H₂O_(l) â†’ CO_(g) + H_2(g)
B 2Na_(s) + 2H₂O_(l) → 2NaOH_(aq) + H_2(g)
C Zn_{(s) + 2HCI[sub](aq)} â†’ ZnCI_2(aq) + H_2(g)[/sub]
D Cu_(s) + H₂O_(l) â†’ CuO_(s) + H_2(g)
E 2AI_(s) + 3H₂O_{(l) â†’ Al[sub]2}O_3(s) + 3H_2(g)[/sub]

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Question 58:

Which of the following statements best explains cracking ? It is a process

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A In which an alkene adds on itself repeatedly to form long chain polymers
B In which large hydrocarbon molecules are broken into smaller units
C For measuring theoctane number of petrol
D In which carbon chain results in a zigzag arrangement
E In which aromatic hydrocarbons are produced

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Question 59:

120cm³ of hydrogen were sparked with 60cm ³ of oxygen at 110^oC. What was the volume of stream produced? The equation for the reaction is 2H_2(g) + O_2(g) â†’ 2H₂O_(g)

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A 30cm₃
B 60cm₃
C 90cm₃
D 120cm₃
E 180cm₃

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Question 60:

The earthly impurities in iron ore are removed in the blast furnace by the reaction

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A CO₂ + C â†’2CO
B Fe₂O₃ + 3CO →2Fe + 3CO₂
C SiO₂ + CaO â†’CaSiO₃
D CaCO₃ â†’ CaO + CO₂
E C +CO₂ â†’ CO₂

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