POST UTME LAUTECH 2017 Chemistry | Objective

Are you preparing for POST UTME LAUTECH exams? Reviewing past questions is one of the most effective ways to guarantee a high score. This practice hub features authentic 2017 Chemistry (Objective) questions designed to simulate the real exam environment.

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Question 1
Determine the molar solubility of AgCl in a solution containing 0.1 M NaCl. The solubility product cons\tant (Ksp) for AgCl is 1.8 x 10^-10.
Correct A. 1.0 x 10^-5 M
B. 1.0 x 10^-6 M
C. 1.0 x 10^-7 M
D. 1.0 x 10^-8 M

Correct Answer: A

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Question 2
A 1.0 L solution contains 0.5 M NH3. What is the concentration of NH4+ ions in the solution?
A. 0.5 M
Correct B. 0.25 M
C. 0.1 M
D. 0.05 M

Correct Answer: B

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Question 3
A 2.0 L solution contains 0.2 M H2SO4. What is the concentration of H+ ions in the solution?
A. 0.1 M
Correct B. 0.2 M
C. 0.4 M
D. 0.8 M

Correct Answer: B

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Question 4
A 1.0 L solution contains 0.5 M NaOH. What is the concentration of OH- ions in the solution?
Correct A. 0.5 M
B. 0.25 M
C. 0.1 M
D. 0.05 M

Correct Answer: A

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Question 5
A 2.0 L solution contains 0.2 M HCl. What is the concentration of H+ ions in the solution?
A. 0.1 M
Correct B. 0.2 M
C. 0.4 M
D. 0.8 M

Correct Answer: B

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Question 6
The atomic radius of an element in the periodic table generally increases down a group due to the addition of new energy levels. However, the atomic radius of an element in the periodic table generally decreases across a period due to the increase in effective nuclear charge. Which of the following elements has the largest atomic radius?
A. Rb
B. Cs
C. Fr
Correct D. Ba

Correct Answer: D

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Question 7
The reaction of an alkane with chlorine gas in the presence of light produces a chlorinated product. Which of the following reactions represents the correct mechanism for this reaction?
A. \( \text{CH}_4 + \text{Cl}_2 \rightarrow \text{CH}_3\text{Cl} + \text{HCl} \)
B. \( \text{CH}_4 + \text{Cl}_2 \rightarrow \text{CH}_2\text{Cl}_2 + \text{H}_2 \)
Correct C. \( \text{CH}_4 + \text{Cl}_2 \rightarrow \text{CHCl}_3 + \text{HCl} \)
D. \( \text{CH}_4 + \text{Cl}_2 \rightarrow \text{CCl}_4 + \text{H}_2 \)

Correct Answer: C

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Question 8
The s\tandard enthalpy of formation of a compound is the enthalpy change when one mole of the compound is formed from its constituent elements in their s\tandard states. Which of the following compounds has a negative s\tandard enthalpy of formation?
Correct A. \( \text{H}_2\text{O}\( \text{l} \ \) )
B. \( \text{CO}_2\( \text{g} \ \) )
C. \( \text{NH}_3\( \text{g} \ \) )
D. \( \text{O}_2\( \text{g} \ \) )

Correct Answer: A

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Question 9
The entropy of a subs\tance is a measure of its disorder or randomness. Which of the following subs\tances has the highest entropy?
A. \( \text{H}_2\text{O}\( \text{l} \ \) )
B. \( \text{CO}_2\( \text{g} \ \) )
C. \( \text{NH}_3\( \text{g} \ \) )
Correct D. \( \text{O}_2\( \text{g} \ \) )

Correct Answer: D

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Question 10
The periodic table is arranged in a way that elements with similar properties are placed in the same group. Which of the following elements is a member of group 17?
A. \( \text{Na} \)
B. \( \text{Mg} \)
Correct C. \( \text{Cl} \)
D. \( \text{K} \)

Correct Answer: C

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Question 11
Calculate the s\tandard enthalpy change \( ΔH^circ \) for the reaction: 2Al(s) + 3H_2O(g) → 2Al(OH)_3(s) + 3/2H_2(g). Given that ΔH^circ_f = -1261.3 kJ/mol for Al(OH)_3(s) and ΔH^circ_f = 0 kJ/mol for Al(s) and H_2O(g).
Correct A. -1478.6 kJ/mol
B. -1261.3 kJ/mol
C. -1478.6 kJ/mol + 0 kJ/mol
D. -1261.3 kJ/mol + 0 kJ/mol

Correct Answer: A

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Question 12
The reaction of 2.5 g of an unknown organic compound with 100.0 mL of 0.5 M NaOH(aq) produces 1.25 g of a precipitate. If the molar mass of the unknown compound is 56.0 g/mol, what is its empirical formula?
Correct A. C_2H_4O
B. C_2H_6O
C. C_3H_6O
D. C_4H_8O

Correct Answer: A

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Question 13
A 1.0 M solution of H_2SO_4(aq) is mixed with a 1.0 M solution of NaOH(aq) in a 1:1 mole ratio. What is the concentration of the resulting solution?
Correct A. 0.5 M
B. 1.0 M
C. 1.5 M
D. 2.0 M

Correct Answer: A

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Question 14
The half-life of a radioactive subs\tance is 5.0 years. If 100 g of the subs\tance is initially present, how much will remain after 10 years?
A. 50 g
Correct B. 25 g
C. 12.5 g
D. 6.25 g

Correct Answer: B

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Question 15
A 2.0 M solution of HCl(aq) is mixed with a 2.0 M solution of NaOH(aq) in a 1:1 mole ratio. What is the concentration of the resulting solution?
A. 0.5 M
Correct B. 1.0 M
C. 1.5 M
D. 2.0 M

Correct Answer: B

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Question 16
The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. Calculate the s\tandard enthalpy of formation of CaCO3(s) u\sing the following reaction: CaO(s) + CO2(g) → CaCO3(s).
Correct A. -1206.5 kJ/mol
B. -393.5 kJ/mol
C. 393.5 kJ/mol
D. 1206.5 kJ/mol

Correct Answer: A

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Question 17
A 2.50 L flask contains 0.150 mol of an ideal gas at 298 K. Calculate the pressure of the gas u\sing the ideal gas law.
Correct A. 1.01 atm
B. 2.02 atm
C. 3.03 atm
D. 4.04 atm

Correct Answer: A

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Question 18
The half-life of a radioactive subs\tance is 5.00 days. If 100.0 mg of the subs\tance initially exists, how much will remain after 20.0 days?
Correct A. 12.5 mg
B. 25.0 mg
C. 37.5 mg
D. 50.0 mg

Correct Answer: A

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Question 19
A 0.500 L flask contains 0.100 mol of an ideal gas at 298 K. If the gas is heated to 373 K, what is the new volume of the gas?
A. 0.500 L
B. 0.750 L
Correct C. 1.00 L
D. 1.25 L

Correct Answer: C

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Question 20
A 2.00 L flask contains 0.200 mol of an ideal gas at 298 K. If the gas is compressed to 1.00 L, what is the new pressure of the gas?
A. 2.02 atm
B. 4.04 atm
Correct C. 6.06 atm
D. 8.08 atm

Correct Answer: C

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Question 21
A 0.500 L flask contains 0.100 mol of an ideal gas at 298 K. If the gas is heated to 373 K, what is the new pressure of the gas?
A. 1.01 atm
Correct B. 2.02 atm
C. 3.03 atm
D. 4.04 atm

Correct Answer: B

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Question 22
A 2.00 L flask contains 0.200 mol of an ideal gas at 298 K. If the gas is compressed to 1.00 L, what is the new temperature of the gas?
A. 298 K
B. 373 K
Correct C. 448 K
D. 523 K

Correct Answer: C

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Question 23
A 0.500 L flask contains 0.100 mol of an ideal gas at 298 K. If the gas is heated to 373 K, what is the new volume of the gas?
A. 0.500 L
B. 0.750 L
Correct C. 1.00 L
D. 1.25 L

Correct Answer: C

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Question 24
A 2.00 L flask contains 0.200 mol of an ideal gas at 298 K. If the gas is compressed to 1.00 L, what is the new pressure of the gas?
A. 2.02 atm
B. 4.04 atm
Correct C. 6.06 atm
D. 8.08 atm

Correct Answer: C

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Question 25
A sample of an ideal gas is heated at cons\tant volume. Which of the following statements is true about the change in the gas's properties?
A. The gas expands and its pressure increases.
B. The gas contracts and its pressure decreases.
Correct C. The gas expands and its pressure remains cons\tant.
D. The gas contracts and its pressure increases.

Correct Answer: C

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