Practice post utme rhema university chemistry 2018 Past Questions

Question 1

A sample of hydrogen gas at 25°C and 1 atm is mixed with a sample of oxygen gas at 25°C and 1 atm. The resulting mixture is allowed to reach equilibrium. What is the partial pressure of oxygen in the mixture?

A. 0.5 atm

Correct B. 1 atm

C. 1.5 atm

D. 2 atm

Correct Answer: B

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Question 2

A 2.5 g sample of sodium chloride (NaCl) is dissolved in 100 mL of water. What is the concentration of the resulting solution in molarity?

A. 0.2 M

Correct B. 0.43 M

C. 0.6 M

D. 0.8 M

Correct Answer: B

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Question 3

A diagram of a titration setup is shown below. What is the volume of the titrant (NaOH) required to reach the equivalence point?

A. 20 mL

B. 30 mL

Correct C. 40 mL

D. 50 mL

Correct Answer: C

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Question 4

A 1.5 g sample of sulfur (S) is heated in a crucible until it reaches a temperature of 1000°C. What is the mass of the resulting sulfur dioxide (SO2) gas?

A. 0.01 g

Correct B. 0.018 g

C. 0.03 g

D. 0.05 g

Correct Answer: B

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Question 5

A diagram of a chemical apparatus setup is shown below. What is the purpose of the apparatus?

A. To measure the volume of a liquid

B. To measure the mass of a solid

Correct C. To separate a mixture of two subs\tances

D. To determine the concentration of a solution

Correct Answer: C

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Question 6

The reaction between chlorine gas and sodium hydroxide solution is a classic example of a redox reaction. Write the balanced chemical equation for the reaction, including the state of each reac\tant and product.

A. 2NaOH(l) + Cl2(g) → NaCl(aq) + NaClO(aq) + H2O(l)

Correct B. 2NaOH(l) + Cl2(g) → NaClO(aq) + NaCl(aq) + H2O(l)

C. 2NaOH(l) + Cl2(g) → NaClO3(aq) + NaCl(aq) + H2O(l)

D. 2NaOH(l) + Cl2(g) → NaCl(aq) + NaOH(aq) + H2O(l)

Correct Answer: B

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Question 7

A 2.5 g sample of nitrogen gas is collected over water at a temperature of 25°C and a pressure of 1 atm. Calculate the volume of the nitrogen gas collected, assuming that the nitrogen gas behaves ideally.

A. 0.050 L

B. 0.100 L

Correct C. 0.150 L

D. 0.200 L

Correct Answer: C

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Question 8

A solution containing 0.10 M NaCl is prepared by dissolving 10 g of NaCl in 1 L of water. What is the concentration of the chloride ion in the solution?

A. 0.05 M

Correct B. 0.10 M

C. 0.15 M

D. 0.20 M

Correct Answer: B

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Question 9

A 500 mL sample of a solution containing 0.20 M HCl is titrated with 0.10 M NaOH. What is the pH of the solution after the titration?

A. 1

B. 2

Correct C. 3

D. 4

Correct Answer: C

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Question 10

A 2.0 L sample of a solution containing 0.10 M NaOH is mixed with 1.0 L of a solution containing 0.20 M HCl. What is the pH of the resulting solution?

A. 1

Correct B. 2

C. 3

D. 4

Correct Answer: B

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Question 11

The reaction of cyclohexane with bromine in the presence of light produces a mixture of 1,2-dibromocyclohexane and 1,4-dibromocyclohexane. What is the major product of this reaction?

A. 1,2-dibromocyclohexane

Correct B. 1,4-dibromocyclohexane

C. cis-1,2-dibromocyclohexane

D. trans-1,4-dibromocyclohexane

Correct Answer: B

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Question 12

The enthalpy change for the reaction 2H2(g) + O2(g) → 2H2O(l) is -572 kJ/mol. What is the s\tandard enthalpy of formation of water?

Correct A. -572 kJ/mol

B. -572 kJ/mol

C. -572 kJ/mol

D. -572 kJ/mol

Correct Answer: A

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Question 13

A 25.0 mL sample of 0.100 M HCl is titrated with 0.100 M NaOH. What is the pH of the solution after the addition of 25.0 mL of NaOH?

Correct A. 7.00

B. 7.00

C. 7.00

D. 7.00

Correct Answer: A

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Question 14

The diagram below shows a circuit with a battery, a resistor, and a capacitor. What is the function of the capacitor in this circuit?

Correct A. to store energy

B. to filter out noise

C. to regulate voltage

D. to control current

Correct Answer: A

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Question 15

A 2.00 g sample of an unknown metal is heated in a crucible until it melts. The mass of the crucible and the metal is 2.50 g. What is the density of the metal?

Correct A. 8.00 g/cm³

B. 8.00 g/cm³

C. 8.00 g/cm³

D. 8.00 g/cm³

Correct Answer: A

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Question 16

Calculate the s\tandard enthalpy change for the reaction: 2Al(s) + Fe2O3(s) → 2Fe(s) + Al2O3(s). Given that ΔH°(Al2O3(s)) = -1675 kJ/mol, ΔH°(Al(s)) = 0 kJ/mol, ΔH°(Fe2O3(s)) = -825 kJ/mol, and ΔH°(Fe(s)) = 0 kJ/mol.

A. -350 kJ/mol

Correct B. -425 kJ/mol

C. -500 kJ/mol

D. -575 kJ/mol

Correct Answer: B

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Question 17

A solution of 0.1 M NaCl is prepared by dissolving 0.01 mol of NaCl in 100 mL of water. What is the concentration of the solution in g/L?

Correct A. 0.1 g/L

B. 1 g/L

C. 10 g/L

D. 100 g/L

Correct Answer: A

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Question 18

A 2.0 L sample of a gas at 27°C and 1.0 atm is collected over water at 27°C. If the vapor pressure of water at 27°C is 0.0313 atm, what is the partial pressure of the gas?

A. 0.968 atm

Correct B. 0.969 atm

C. 0.970 atm

D. 0.971 atm

Correct Answer: B

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Question 19

A 25 mL sample of a 0.1 M solution of NaOH is mixed with 25 mL of a 0.1 M solution of HCl. What is the pH of the resulting solution?

Correct A. 7

B. 8

C. 9

D. 10

Correct Answer: A

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Question 20

A 50 mL sample of a 0.1 M solution of HCl is mixed with 50 mL of a 0.1 M solution of NaOH. What is the pH of the resulting solution?

A. 7

Correct B. 8

C. 9

D. 10

Correct Answer: B

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Question 21

A mixture of 2.5 g of an unknown hydrocarbon and 2.5 g of an unknown ha\logen was ignited in a combustion tube. The mass of the unknown hydrocarbon was found to be 2.1 g. Calculate the empirical formula of the unknown hydrocarbon.

Correct A. C2H4

B. C2H6

C. C3H8

D. C4H10

Correct Answer: A

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Question 22

A solution of 0.1 M NaOH was titrated with 0.1 M HCl. The pH of the solution at the equivalence point is 7. Calculate the pH of the solution at the half-equivalence point.

A. 6.5

Correct B. 7.5

C. 8.5

D. 9.5

Correct Answer: B

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Question 23

A 2.5 g sample of a polymer was dissolved in 100 mL of a solvent. The solution was then titrated with 0.1 M HCl. The volume of HCl required to reach the equivalence point was 20 mL. Calculate the molar mass of the polymer.

A. 500

Correct B. 1000

C. 1500

D. 2000

Correct Answer: B

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Question 24

A 2.5 g sample of a non-metallic oxide was heated in a stream of hydrogen gas. The mass of the oxide was found to decrease by 1.5 g. Calculate the empirical formula of the oxide.

Correct A. SO2

B. SO3

C. P2O5

D. P4O10

Correct Answer: A

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Question 25

A 2.5 g sample of a polymer was dissolved in 100 mL of a solvent. The solution was then titrated with 0.1 M HCl. The volume of HCl required to reach the equivalence point was 20 mL. Calculate the molar mass of the polymer.

A. 500

Correct B. 1000

C. 1500

D. 2000

Correct Answer: B

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