POST UTME DELSU 2018 Chemistry | Objective

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Question 1
Determine the rate cons\tant (k) for the reaction: 2NO(g) + O2(g) → 2NO2(g), given that the initial concentrations of NO and O2 are 0.5 M and 0.2 M, respectively, and the rate of reaction is 0.02 M/s after 10 minutes.
A. \( k = 0.02 , \text{M/s} \)
B. \( k = 0.04 , \text{M/s} \)
C. \( k = 0.06 , \text{M/s} \)
D. \( k = 0.08 , \text{M/s} \)
Question 2
A polymer has a molecular weight of 50,000 g/mol and a degree of polymerization of 200. Calculate the molar mass of the repeating unit.
A. \( 100 , \text{g/mol} \)
B. \( 200 , \text{g/mol} \)
C. \( 300 , \text{g/mol} \)
D. \( 400 , \text{g/mol} \)
Question 3
A 25 mL sample of a polymer solution containing 10% \( w/v \) of a polymer is titrated with 0.1 M NaOH. The equivalence point is reached when 25 mL of NaOH has been added. What is the molar mass of the polymer?
A. 1000 g/mol
B. 2000 g/mol
C. 5000 g/mol
D. 10000 g/mol
Question 4
A solution of 0.1 M H2SO4 is titrated with 0.1 M NaOH. If 20 mL of NaOH is added, what is the pH of the resulting solution?
A. 1
B. 2
C. 3
D. 4
Question 5
A sample of benzene (C6H6) has a mass of 10 g. If the molar mass of benzene is 78 g/mol, what is the number of moles of benzene present?
A. 0.1
B. 0.2
C. 0.3
D. 0.4
Question 6
Identify the functional group present in the compound: CH₃CH₂CH₂CH₂OH.
A. Alkyl group
B. Aldehyde group
C. Ketone group
D. Alcohol group
Question 7
A 0.1 M solution of NaOH is prepared by dissolving 4.0 g of NaOH in 100 mL of water. What is the molarity of the solution?
A. 0.1 M
B. 0.2 M
C. 0.3 M
D. 0.4 M
Question 8
A solution of 0.5 M HCl is titrated with 0.5 M NaOH. If 25 mL of NaOH is added, what is the pH of the resulting solution?
A. 1
B. 2
C. 3
D. 4
Question 9
A sample of a gas has a volume of 2.5 L at a pressure of 1.5 atm and a temperature of 300 K. What is the pressure of the gas at a volume of 3.5 L and a temperature of 400 K?
A. 2.0 atm
B. 2.5 atm
C. 3.0 atm
D. 3.5 atm
Question 10
The diagram below represents a titration setup. Identify the subs\tance being titrated.
A. ( HCl )
B. ( NaOH )
C. \( H_2SO_4 \)
D. \( NH_3 \)
Question 11
A metal M (atomic number 23) reacts with oxygen gas to form a white solid. The reaction is as follows: 4M + 3O2 → 2M2O3. If 2.5 g of M is used in the reaction, what is the mass of O2 required?
A. 4.2 g
B. 5.2 g
C. 6.2 g
D. 7.2 g
Question 12
The s\tandard enthalpy of formation (ΔHf) for the compound CO2(g) is -393.5 kJ/mol. If 2.0 mol of CO2 is formed at 298 K, what is the total enthalpy change (ΔH) for the reaction?
A. -787 kJ
B. -786 kJ
C. -785 kJ
D. -784 kJ
Question 13
A 0.1 M solution of NaCl is prepared by dissolving 6.0 g of NaCl in 100 mL of water. What is the molarity of the solution?
A. 0.1 M
B. 0.2 M
C. 0.3 M
D. 0.4 M
Question 14
Determine the rate cons\tant (k) for the reaction: 2NO(g) + O2(g) → 2NO2(g), given that the initial concentrations of NO and O2 are 0.1 M and 0.05 M, respectively, and the rate of disappearance of NO is 2.5 × 10^\( -3 \) M/s.
A. \( 2.5 \times 10^3 \) M^\( -1 \)s^\( -1 \)
B. \( 5.0 \times 10^3 \) M^\( -1 \)s^\( -1 \)
C. \( 1.0 \times 10^4 \) M^\( -1 \)s^\( -1 \)
D. \( 2.0 \times 10^4 \) M^\( -1 \)s^\( -1 \)
Question 15
The s\tandard electrode potential of the cell is 1.5 V. If the cell is connected to a 1.5 V battery, what is the cell potential?
A. 0 V
B. 1.5 V
C. 2.5 V
D. 3.5 V

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