POST UTME KSU 2022 Chemistry | Objective

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Question 1
A metal (M) reacts with chlorine gas to form a white solid. The reaction is as follows: 2M(s) + Cl2(g) → 2MCl(s). If 2.5 g of MCl is produced, what is the mass of M used?
A. 1.25 g
B. 2.5 g
C. 3.75 g
D. 5.0 g
Question 2
A 1.0 M solution of a weak acid, HA, is titrated with 1.0 M NaOH. The initial pH of the solution is 3.0. What is the pH of the solution after the addition of 20 mL of 1.0 M NaOH?
A. 7.0
B. 8.0
C. 9.0
D. 10.0
Question 3
A 0.500 M solution of NaOH is mixed with a 0.500 M solution of HCl. What is the pH of the resulting solution?
A. 1.00
B. 2.00
C. 3.00
D. 4.00
Question 4
A sample of a metal (M) is treated with 10 mL of 1 M HCl. The reaction is complete, and the resulting solution is titrated with 0.1 M NaOH. If 20 mL of NaOH is required to reach the equivalence point, what is the concentration of M in the original sample?
A. 0.1 M
B. 0.2 M
C. 0.3 M
D. 0.4 M
Question 5
A diagram of a titration setup is shown below. If 35.0 mL of 0.100 M NaOH is required to reach the equivalence point, what is the concentration of the HCl solution?
A. 0.100 M
B. 0.200 M
C. 0.500 M
D. 1.00 M
Question 6
The entropy change (ΔS) for the reaction N2(g) + 3H2(g) → 2NH3(g) at 298 K is 199.3 J/K mol. What is the s\tandard enthalpy change (ΔH) for the reaction?
A. -45.9 kJ/mol
B. -92.0 kJ/mol
C. -137.9 kJ/mol
D. -182.0 kJ/mol
Question 7
The atomic radius of an element is the dis\tance from the nucleus to the outermost electron in a neutral atom. What is the unit of atomic radius?
A. pm
B. nm
C. cm
D. m
Question 8
A solution contains 0.1 M NaCl. If 10 mL of this solution is diluted to 100 mL, what is the concentration of the resulting solution?
A. 0.01 M
B. 0.1 M
C. 1 M
D. 10 M
Question 9
The rate cons\tant of a first-order reaction is given by the equation \( k = \frac{2.303}{t} \log_{10} left\( \frac{[A]_0}{[A]_t} \right \ \) ). If the initial concentration of the reac\tant is 0.1 M and the concentration at time t is 0.01 M, calculate the rate cons\tant k.
A. 0.01 min^-1
B. 0.1 min^-1
C. 1 min^-1
D. 10 min^-1
Question 10
The s\tandard enthalpy of formation of H2O(l) is -285.8 kJ/mol. What is the s\tandard enthalpy of formation of H2(g)?
A. 0 kJ/mol
B. 57.8 kJ/mol
C. 114.0 kJ/mol
D. 171.0 kJ/mol
Question 11
A 2.5 g sample of an unknown hydrocarbon is burned in a combustion calorimeter. The temperature of the calorimeter increases by 23.5°C. If the calorimeter cons\tant is 2.5 J/g°C, what is the heat of combustion of the hydrocarbon, assuming it is a pure subs\tance?
A. 100 kJ/mol
B. 200 kJ/mol
C. 300 kJ/mol
D. 400 kJ/mol
Question 12
At 298 K, the s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. Calculate the s\tandard enthalpy of formation of CO(g) if the s\tandard enthalpy of formation of O2(g) is 0 kJ/mol.
A. -110.5 kJ/mol
B. -393.5 kJ/mol
C. 110.5 kJ/mol
D. 393.5 kJ/mol
Question 13
The compound 1,2-dimethylcyclohexane is an example of a branched alkane. Draw the structure of this compound.
A. CH3CH2CH2CH3
B. CH3C(CH3)2CH3
C. CH3CH(CH3)CH3
D. CH3CH2CH(CH3)CH3
Question 14
A 1 M solution of FeCl3 is treated with 10 mL of 1 M NaOH. If the reaction is complete, what is the concentration of Fe(OH)3 in the resulting solution?
A. 0.1 M
B. 0.2 M
C. 0.3 M
D. 0.4 M
Question 15
A sample of nitrogen gas occupies a volume of 2.5 L at a pressure of 1.5 atm and a temperature of 298 K. What is the number of moles of nitrogen gas present?
A. 0.25 mol
B. 0.5 mol
C. 0.75 mol
D. 1.0 mol

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