POST UTME MOUNTAIN TOP UNIVERSITY 2017 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

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 0.1 M and 0.2 M, respectively, and the rate of reaction is 0.05 M/s after 10 minutes.
A. \( k = \frac{2.303}{t} \log \frac{[NO]_0 [O_2]_0}{[NO_2]_t} \)
B. \( k = \frac{2.303}{t} \log \frac{[NO_2]_t}{[NO]_0 [O_2]_0} \)
C. \( k = \frac{2.303}{t} \log \frac{[NO]_0 [O_2]_0}{[NO_2]_t} \)
D. \( k = \frac{2.303}{t} \log \frac{[NO_2]_t}{[NO]_0 [O_2]_0} \)
Question 2
A sample of gas occupies a volume of 2.5 L at a pressure of 1.5 atm. If the temperature is increased to 300 K, what is the new volume of the gas?
A. 3.75 L
B. 2.5 L
C. 1.25 L
D. 4.0 L
Question 3
A 2.5 L sample of a gas at 27°C and 1 atm is collected over water at 27°C. Calculate the partial pressure of the gas.
A. 0.95 atm
B. 0.98 atm
C. 1.02 atm
D. 1.05 atm
Question 4
The process by which water is converted into hydrogen and oxygen is called _______.
A. photosynthesis
B. respiration
C. decomposition
D. electrolysis
Question 5
A 2.0 g sample of sulfur is burned in oxygen to produce sulfur dioxide gas. If the reaction is 100% efficient, what is the volume of SO2 produced at 298 K and 1 atm?
A. 2.4 L
B. 4.8 L
C. 6.2 L
D. 8.5 L
Question 6
A 25.0 mL sample of 0.100 M HCl is titrated with 0.100 M NaOH. Calculate the pH of the solution after 25.0 mL of NaOH has been added.
A. \( pH = -\log[H^+] \)
B. \( pH = -\log[OH^-] \)
C. \( pH = \log \frac{[H^+]}{[OH^-]} \)
D. \( pH = \log \frac{[OH^-]}{[H^+]} \)
Question 7
A 1.0 M solution of NaOH is mixed with a 1.0 M solution of HCl. If 50.0 mL of the NaOH solution is added to 50.0 mL of the HCl solution, what is the concentration of the resulting solution?
A. 0.5 M
B. 1.0 M
C. 1.5 M
D. 2.0 M
Question 8
The rate cons\tant of a first-order reaction is given by the equation: k = 2.303/t \log10\( A0/A \). If the initial concentration of a reac\tant is 0.1 M and the concentration after 10 minutes is 0.05 M, calculate the rate cons\tant (k) of the reaction.
A. 0.0005 min^-1
B. 0.001 min^-1
C. 0.005 min^-1
D. 0.01 min^-1
Question 9
A polymer is a long chain of _______ molecules.
A. monomers
B. polymers
C. atoms
D. molecules
Question 10
A 0.1 M solution of HCl is titrated with 0.1 M NaOH. What is the pH of the solution after 50 mL of NaOH has been added?
A. 1
B. 2
C. 3
D. 4
Question 11
A 2.0 g sample of a metal is heated in a crucible until it is completely oxidized to form a metal oxide. The mass of the oxide formed is 3.2 g. Calculate the percentage of the metal in the oxide.
A. 62%
B. 70%
C. 80%
D. 90%
Question 12
A gas at 25°C and 1 atm is compressed to 4 atm. Calculate the new volume of the gas.
A. \( V_1 P_1 = V_2 P_2 \)
B. \( \frac{P_1 V_1}{T_1} = \frac{P_2 V_2}{T_2} \)
C. \( \frac{P_1 V_1}{T_1} = \frac{P_2 V_2}{T_2} \)
D. \( \frac{P_1 V_1}{T_1} = \frac{P_2 V_2}{T_2} \)
Question 13
A 2.0 g sample of sulfur is burned in oxygen to produce sulfur dioxide gas. If the reaction is 100% efficient, what is the volume of SO2 produced at 298 K and 1 atm?
A. 2.4 L
B. 4.8 L
C. 6.2 L
D. 8.5 L
Question 14
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. -130.5 kJ/mol
C. -140.5 kJ/mol
D. -150.5 kJ/mol
Question 15
A solution contains 2.5g of NaCl in 100g of water. What is the molarity of the solution?
A. 0.1M
B. 0.2M
C. 0.3M
D. 0.4M

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