Chemistry Assessment 013125

Which of the following best describes chemical equilibrium?

The reaction stops completely

Correct Incorrect Correct answer

The concentrations of reactants and products become equal

Correct Incorrect Correct answer

The rate of the forward reaction equals the rate of the reverse reaction

Correct Incorrect Correct answer

The amount of reactants is always greater than the products

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What is the equilibrium constant expression for the reaction:

?_{2}(?) + 3?2(?) ⇌ 2??_{3} (?)

Kc = \frac{[N_{2}][H_{2}]^{3}}{[NH_{3}]^{2}}

Correct Incorrect Correct answer

Kc = \frac{[NH_{3}]^{2}}{[N_{2}][H_{2}]^{3}}

Correct Incorrect Correct answer

Kc = \frac{[NH_{3}]}{[N_{2}][H_{2}]}

Correct Incorrect Correct answer

Kc = \frac{[N_{2}][H_{2}]}{[NH_{3}]}

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According to Le Chatelier’s Principle, what happens if the concentration of a reactant is increased?

The equilibrium shifts to the right

Correct Incorrect Correct answer

The equilibrium shifts to the left

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The equilibrium remains unchanged

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The reaction stops

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Which of the following metals is extracted using electrolysis?

Iron

Correct Incorrect Correct answer

Copper

Correct Incorrect Correct answer

Aluminium

Correct Incorrect Correct answer

Zinc

Correct Incorrect Correct answer

The main ore of iron is:

Bauxite

Correct Incorrect Correct answer

Galena

Correct Incorrect Correct answer

Haematite

Correct Incorrect Correct answer

Cryolite

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Which reducing agent is used in the extraction of iron in the blast furnace?

Carbon monoxide

Correct Incorrect Correct answer

Carbon dioxide

Correct Incorrect Correct answer

Oxygen

Correct Incorrect Correct answer

Sulphur dioxide

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Which of the following statements about the extraction of zinc is correct?

Zinc is extracted from zinc blende using electrolysis

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Zinc oxide is reduced using coke

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Zinc is extracted from haematite

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Zinc does not require reduction

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What is the major impurity removed in the extraction of iron in a blast furnace?

Sand (SiO₂)

Correct Incorrect Correct answer

Carbon dioxide

Correct Incorrect Correct answer

Magnesium oxide

Correct Incorrect Correct answer

Sulphur dioxide

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The solubility of KCl in water at 25°C is 34.0 g per 100 g of water. What is the maximum mass of KCl that can dissolve in 250 g of water?

34.0 g

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85.0 g

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68.0 g

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17.0 g

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Which unit is commonly used to express solubility?

g/mL

Correct Incorrect Correct answer

g/L

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mol/kg

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None of the above

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If 0.05 mol of PbI₂ dissolves in 1 L of water, what is its solubility in g/L? (Molar mass of PbI₂ = 461 g/mol)

0.05 g/L

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23.05 g/L

Correct Incorrect Correct answer

46.1 g/L

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9.22 g/L

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Which of the following nuclear emissions has the highest penetrating power?

Alpha particles

Correct Incorrect Correct answer

Beta particles

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Gamma rays

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Neutrons

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Which of the following equations correctly represents the decay of Uranium-238?

^{238}U → ^{234}Th + α

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^{238}U → ^{234}Th + e^{−}

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^{238}U → ^{234}Th + β^{−}

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^{238}U → ^{234}Th + γ

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What is the half-life of a sample if only 25% of the radioactive material remains after 10 hours?

2.5 hours

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5 hours

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10 hours

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15 hours

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A radioactive sample has a half-life of 4 hours. How much of a 200 g sample remains after 12 hours?

25 g

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50 g

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100 g

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Which nuclear reaction is used in nuclear power plants?

Nuclear fusion

Correct Incorrect Correct answer

Alpha decay

Correct Incorrect Correct answer

Nuclear fission

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Beta decay

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Which of the following is a suitable electrolyte for the electrolysis of water?

Pure water

Correct Incorrect Correct answer

Sugar solution

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Dilute sulphuric acid

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Sodium chloride

Correct Incorrect Correct answer

What is produced at the cathode during the electrolysis of molten NaCl?

Chlorine gas

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Hydrogen gas

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Sodium metal

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Oxygen gas

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If a current of 10 A is passed through CuSO₄ solution for 30 minutes, how much copper is deposited?

5.93 g

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10.63 g

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2.97 g

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1.98 g

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In the electrolysis of aqueous CuSO₄ using copper electrodes, which statement is true?

Copper is deposited at the anode

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Copper ions move to the anode

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The mass of the cathode increases

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The color of the solution changes from blue to green

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Chemistry Assessment 013125

Stephen January 31, 2025

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