Practice Post UTME LEAD CITY UNIVERSITY chemistry 2020 Past Questions

Question 1

A 0.5 M solution of NaOH is prepared by dissolving 3.5 g of NaOH in 1000 mL of water. What is the molarity of the solution if 10 mL of the solution is diluted to 100 mL with water?

A. 0.3 M

Correct B. 0.35 M

C. 0.4 M

D. 0.45 M

Correct Answer: B

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Question 2

A 25 mL sample of a 0.1 M solution of HCl is titrated with 0.1 M NaOH. What is the pH of the solution after the addition of 20 mL of NaOH?

A. 1.0

B. 2.0

Correct C. 3.0

D. 4.0

Correct Answer: C

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Question 3

A 10 mL sample of a 0.5 M solution of H2SO4 is titrated with 0.5 M NaOH. What is the pH of the solution after the addition of 20 mL of NaOH?

A. 1.0

B. 2.0

C. 3.0

Correct D. 4.0

Correct Answer: D

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Question 4

A 25 mL sample of a 0.1 M solution of HCl is titrated with 0.1 M NaOH. What is the pH of the solution after the addition of 25 mL of NaOH?

A. 1.0

Correct B. 2.0

C. 3.0

D. 4.0

Correct Answer: B

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Question 5

A 10 mL sample of a 0.5 M solution of H2SO4 is titrated with 0.5 M NaOH. What is the pH of the solution after the addition of 10 mL of NaOH?

A. 1.0

Correct B. 2.0

C. 3.0

D. 4.0

Correct Answer: B

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Question 6

The atomic radius of an element is 100 pm. If the element is in the 3rd period of the periodic table, what is the expected value of its atomic radius in the 4th period?

Correct A. 120 pm

B. 110 pm

C. 130 pm

D. 140 pm

Correct Answer: A

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Question 7

A sample of gas at 25°C and 1 atm is allowed to expand to twice its original volume. What is the new pressure of the gas?

A. 0.5 atm

B. 1 atm

Correct C. 2 atm

D. 4 atm

Correct Answer: C

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Question 8

The compound SO2 is a toxic gas. What is the oxidation state of sulfur in this compound?

A. +2

B. -2

Correct C. +4

D. -4

Correct Answer: C

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Question 9

A polymer is a long chain of repeating units. What is the name of the repeating unit in the polymer polyethylene?

Correct A. Ethylene

B. Polyethylene

C. Ethane

D. Propane

Correct Answer: A

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Question 10

A solution of HCl is titrated with a solution of NaOH. What is the pH of the solution after the titration is complete?

A. 7

Correct B. 10

C. 14

D. 0

Correct Answer: B

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Question 11

A 2.50 g sample of a hydrocarbon, C_xH_y, is burned in a combustion apparatus. The volume of CO2 produced is 2.00 L at STP. If the molar mass of the hydrocarbon is 42.0 g/mol, what is the empirical formula of the hydrocarbon?

Correct A. C2H6

B. C3H8

C. C4H10

D. C5H12

Correct Answer: A

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Question 12

A solution of HCl is added to a solution of NaOH. The reaction is as follows: HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l). If 25.0 mL of 1.00 M HCl is added to 25.0 mL of 1.00 M NaOH, what is the concentration of the resulting solution?

A. 0.50 M

Correct B. 1.00 M

C. 1.50 M

D. 2.00 M

Correct Answer: B

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Question 13

A 2.00 L flask contains 0.500 mol of N2 and 0.250 mol of O2 at 25°C. If the reaction 2N2(g) + O2(g) → 2N2O(g) is allowed to proceed until equilibrium is reached, what is the concentration of N2O in the flask?

A. 0.125 M

B. 0.250 M

Correct C. 0.375 M

D. 0.500 M

Correct Answer: C

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Question 14

A 1.00 L flask contains 0.500 mol of H2 and 0.250 mol of I2 at 25°C. If the reaction 2H2(g) + I2(g) → 2HI(g) is allowed to proceed until equilibrium is reached, what is the concentration of HI in the flask?

A. 0.125 M

B. 0.250 M

C. 0.375 M

Correct D. 0.500 M

Correct Answer: D

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Question 15

A 2.00 L flask contains 0.500 mol of CO and 0.250 mol of O2 at 25°C. If the reaction CO(g) + 1/2O2(g) → CO2(g) is allowed to proceed until equilibrium is reached, what is the concentration of CO2 in the flask?

A. 0.125 M

B. 0.250 M

Correct C. 0.375 M

D. 0.500 M

Correct Answer: C

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Question 16

A 1.00 L flask contains 0.500 mol of H2 and 0.250 mol of F2 at 25°C. If the reaction 2H2(g) + F2(g) → 2HF(g) is allowed to proceed until equilibrium is reached, what is the concentration of HF in the flask?

A. 0.125 M

B. 0.250 M

C. 0.375 M

Correct D. 0.500 M

Correct Answer: D

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Question 17

A 2.00 L flask contains 0.500 mol of N2 and 0.250 mol of O2 at 25°C. If the reaction 2N2(g) + O2(g) → 2N2O(g) is allowed to proceed until equilibrium is reached, what is the concentration of N2O in the flask?

A. 0.125 M

B. 0.250 M

Correct C. 0.375 M

D. 0.500 M

Correct Answer: C

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Question 18

A 1.00 L flask contains 0.500 mol of H2 and 0.250 mol of I2 at 25°C. If the reaction 2H2(g) + I2(g) → 2HI(g) is allowed to proceed until equilibrium is reached, what is the concentration of HI in the flask?

A. 0.125 M

B. 0.250 M

C. 0.375 M

Correct D. 0.500 M

Correct Answer: D

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Question 19

Determine the pH of a 0.1 M solution of HCl, given that the dissociation cons\tant of HCl is 10^\( -7 \).

A. 1

B. 2

C. 3

Correct D. 4

Correct Answer: D

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Question 20

A 25 mL sample of 0.2 M NaOH is titrated with 0.1 M HCl. Calculate the pH of the solution after 10 mL of HCl has been added.

A. 2

B. 3

Correct C. 4

D. 5

Correct Answer: C

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Question 21

A solution of 0.1 M H2SO4 is prepared by dissolving 0.1 mol of H2SO4 in 1 L of water. Calculate the concentration of H+ ions in the solution.

A. 0.01

Correct B. 0.1

C. 1

D. 10

Correct Answer: B

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Question 22

A 10 mL sample of 0.5 M NaOH is titrated with 0.1 M HCl. Calculate the pH of the solution after 20 mL of HCl has been added.

A. 1

B. 2

Correct C. 3

D. 4

Correct Answer: C

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Question 23

A solution of 0.1 M HCl is prepared by dissolving 0.1 mol of HCl in 1 L of water. Calculate the concentration of Cl- ions in the solution.

A. 0.01

Correct B. 0.1

C. 1

D. 10

Correct Answer: B

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Question 24

Determine the number of moles of sulfur dioxide (SO2) produced when 2.5 moles of sulfur (S) react with oxygen (O2) according to the equation: 2S + O2 → 2SO2. Given that the molar mass of S is 32.07 g/mol and the molar mass of SO2 is 64.07 g/mol.

A. 1.25 moles

B. 2.5 moles

Correct C. 3.75 moles

D. 5 moles

Correct Answer: C

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Question 25

A 2.5 L flask contains 0.5 mol of an ideal gas at 27°C. Calculate the pressure of the gas u\sing the ideal gas law: PV = nRT. Given that R = 0.0821 L atm/mol K.

A. 1.7 atm

B. 2.1 atm

Correct C. 2.5 atm

D. 3.1 atm

Correct Answer: C

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