POST UTME DELSU 2023 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. Calculate the s\tandard enthalpy of combustion of 1 mole of methane (CH4(g)) at 298 K.
A. -890 kJ/mol
B. -890.5 kJ/mol
C. -891 kJ/mol
D. -891.5 kJ/mol
Question 2
A 2.5 M solution of sodium hydroxide (NaOH) is titrated with a 2.5 M solution of hydrochloric acid (HCl). Calculate the volume of HCl required to neutralize 25 mL of NaOH.
A. 12.5 mL
B. 25 mL
C. 37.5 mL
D. 50 mL
Question 3
Determine the number of moles of electrons transferred in the reaction: Zn(s) + Cu2+(aq) → Zn2+(aq) + Cu(s). Given that 2.5 g of Zn is used and the reaction occurs at 25°C.
A. 1 mole
B. 2 moles
C. 3 moles
D. 4 moles
Question 4
A 0.1 M solution of HCl is prepared by dissolving 2 g of HCl in 100 mL of water. What is the concentration of the solution in g/L?
A. 0.2 g/L
B. 0.4 g/L
C. 0.6 g/L
D. 0.8 g/L
Question 5
A 0.1 M solution of NaOH is prepared by dissolving 4 g of NaOH in 100 mL of water. What is the concentration of the solution in g/L?
A. 0.4 g/L
B. 0.8 g/L
C. 1.2 g/L
D. 1.6 g/L
Question 6
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. 25 g
C. 12.5 g
D. 6.25 g
Question 7
A metal has a s\tandard enthalpy of formation of -200 kJ/mol. What is the s\tandard enthalpy of combustion of the metal?
A. -100 kJ/mol
B. -150 kJ/mol
C. -200 kJ/mol
D. -250 kJ/mol
Question 8
A metal oxide has the formula MO2. If the metal has an oxidation state of +2, what is the charge on the oxide ion?
A. -2
B. +2
C. -4
D. +4
Question 9
A 2.5 M solution of sodium hydroxide (NaOH) is titrated with a 2.5 M solution of hydrochloric acid (HCl). Calculate the pH of the solution after 25 mL of HCl has been added.
A. 7
B. 8
C. 9
D. 10
Question 10
A gas has a volume of 2.5 L at a pressure of 1.5 atm. What is the volume of the gas at a pressure of 3.0 atm?
A. 1.5 L
B. 2.0 L
C. 2.5 L
D. 3.0 L
Question 11
Determine the pH of a 0.1 M solution of HCl at 25°C, given that the dissociation cons\tant of HCl is 10^\( -7 \) and the temperature dep\endence of the dissociation cons\tant is described by the equation \( \log_{10} K_a = -\frac{1000}{4.57} left\( \frac{1}{T} - \frac{1}{298} \right \ \) ).
A. 1
B. 2
C. 3
D. 4
Question 12
A 0.1 M solution of NaOH is titrated with 0.1 M HCl. Calculate the pH of the solution after 20 mL of HCl has been added.
A. 1
B. 2
C. 3
D. 4
Question 13
Determine the rate cons\tant (k) for the first-order reaction: A → B, given that the initial concentration of A is 0.1 M and the concentration of A after 2 minutes is 0.05 M.
A. \( k = \frac{2.303}{t} \log \frac{[A]_0}{[A]_t} \)
B. \( k = \frac{[A]_t}{[A]_0} \)
C. \( k = \frac{t}{[A]_0} \)
D. \( k = \frac{2.303}{t} \log \frac{[A]_t}{[A]_0} \)
Question 14
A 25 mL sample of 0.5 M HCl is titrated with 0.5 M NaOH. Calculate the volume of NaOH required to reach the equivalence point.
A. 10 mL
B. 20 mL
C. 25 mL
D. 30 mL
Question 15
A solution containing 10 g of glu\cose (C6H12O6) is prepared by dissolving the glu\cose in 100 mL of water. What is the concentration of the solution in g/L?
A. 10 g/L
B. 20 g/L
C. 30 g/L
D. 40 g/L

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