POST UTME NOUN 2022 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
A 2.00-g sample of a metal is dissolved in 10.0 mL of acid. The resulting solution is then titrated with 0.100 M NaOH. If 25.0 mL of NaOH is required to reach the equivalence point, what is the molar mass of the metal?
A. 50.0 g/mol
B. 60.0 g/mol
C. 70.0 g/mol
D. 80.0 g/mol
Question 2
A sample of a polymer (X) has a molecular weight of 5000 g/mol. If 1 g of X is dissolved in 100 mL of water, what is the concentration of the solution in g/L?
A. 50
B. 100
C. 150
D. 200
Question 3
A 25 mL sample of 0.1 M HCl is titrated with 0.1 M NaOH. Calculate the pH of the solution after 20 mL of NaOH has been added.
A. ( 2.303 )
B. ( 4.605 )
C. ( 6.907 )
D. ( 9.209 )
Question 4
A polymer has a molecular weight of 50,000 g/mol and a degree of polymerization of 500. Calculate the molar mass of the repeating unit.
A. 100 g/mol
B. 500 g/mol
C. 1000 g/mol
D. 5000 g/mol
Question 5
A solution contains 5.00 g of NaCl in 250.0 mL of water. What is the molarity of the solution?
A. 0.20 M
B. 0.25 M
C. 0.30 M
D. 0.35 M
Question 6
The half-life of a radioactive subs\tance is 5 years. If a sample of this subs\tance has an initial activity of 100 Bq, what is its activity after 10 years?
A. 12.5 Bq
B. 25 Bq
C. 50 Bq
D. 100 Bq
Question 7
A 2.5 M solution of HCl is titrated with a 1.0 M solution of NaOH. What is the pH of the solution after 25 mL of NaOH has been added?
A. 2.5
B. 3.5
C. 4.5
D. 5.5
Question 8
The rate cons\tant (k) of a first-order reaction is related to the half-life \( t_\( 1/2 \ \)) by the equation: \( k = \frac{ln{2}}{t_{1/2}} \). If the half-life of a reaction is 20 minutes, what is the value of k?
A. 0.0347 min^\( -1 \)
B. 0.0357 min^\( -1 \)
C. 0.0367 min^\( -1 \)
D. 0.0377 min^\( -1 \)
Question 9
A 2.0 M solution of NaOH is prepared by dissolving 40 g of NaOH in 1 L of water. What is the concentration of the solution in terms of molarity?
A. 1.0 M
B. 2.0 M
C. 3.0 M
D. 4.0 M
Question 10
A solution contains 0.1 M HCl and 0.2 M NaOH. What is the pH of the solution?
A. 1.0
B. 2.0
C. 3.0
D. 4.0
Question 11
Determine the rate cons\tant (k) for the reaction: 2NO(g) → N2(g) + O2(g) at 298 K, given that the initial concentration of NO is 0.1 M and the half-life of the reaction is 10 minutes.
A. \( 2.303 \times 10^{-3} , \text{min}^{-1} \)
B. \( 4.606 \times 10^{-3} , \text{min}^{-1} \)
C. \( 6.909 \times 10^{-3} , \text{min}^{-1} \)
D. \( 9.212 \times 10^{-3} , \text{min}^{-1} \)
Question 12
The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. Calculate the s\tandard enthalpy of formation of H2O(l) if the s\tandard enthalpy of formation of H2(g) is 0 kJ/mol and the s\tandard enthalpy of formation of O2(g) is 0 kJ/mol.
A. -241.8 kJ/mol
B. -285.8 kJ/mol
C. -393.5 kJ/mol
D. -285.6 kJ/mol
Question 13
A 1.00-L sample of a gas at 25°C and 1.00 atm is compressed to 2.00 atm at cons\tant temperature. What is the new volume of the gas?
A. 0.50 L
B. 0.75 L
C. 1.00 L
D. 1.25 L
Question 14
A 10.0 mL sample of 0.100 M H2SO4 is titrated with 0.0500 M NaOH. Calculate the pH of the solution at the equivalence point.
A. 1.00
B. 2.00
C. 3.00
D. 4.00
Question 15
The half-life of a radioactive subs\tance is 5 years. If 100 g of the subs\tance is present initially, how much will remain after 10 years?
A. 50 g
B. 75 g
C. 87.5 g
D. 100 g

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