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Chemistry Past Questions and Answers

Waec Chemistry Questions

Question 111:

Which of the following reactions does not occur in the blast furnace during the extraction of iron?

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A Fe₂O₃_(s) + 3CO_(g) â†’ 2Fe_(l) + 3CO₂_(g)
B C₂ + CO ₂_(g)
C CaO_(s) + SiO₂_(s) â†’ CaSiO ₃_(s)
D FeO_(s) + CO₂_(g) + Fe_(l)
E 2Fe₂O_(s) â†’ 4Fe_(l) 3O₂_(g)

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Question 112:

A catayst which increases the rate of a chemical reaction does so by

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A Increasing the reaction pathway
B Increasing the surface area of the reactants
C Increasing the pressure on the system
D Decreasing the temperature at which the reaction occurs
E Decreasing the activation energy of the reaction

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Question 113:

How many molecules are there in 14g of nitrogen gas at s.t.p? (n = 14, Avogadro Number = 6. 0 x 10₂₃ mol_-1)

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A 1.2 x 10 ²³
B 3.0 x 10²³
C 6.0 x10²³
D 1.2 x 10²⁴
E 30 x10²³

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Question 114:

Which of the following correctly explains entropy?

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A The natural tendency for a system to achieve a greater disorder
B A balance of two driving forces between free energy and enthalpy changes
C The cause of spontaneity of a reaction
D A measure of the enthalpy of a reaction
E A measure of the rate of attaining equilibrum in a reversible reaction

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Question 115:

The gas that is liberated when iron is heated with concentrated tetraoxosulphate (VI)acid is

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A H₂S
B \(SO_{2}\)
C HCI
D SO₃
E O₂

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