POST UTME MADONNA UNIVERSITY 2022 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
A 2.5 g sample of a non-metallic oxide is heated in a crucible until it decomposes completely. The mass of the residue is 0.5 g. If the oxide is composed of 60% oxygen by mass, what is the empirical formula of the oxide?
A. MgO
B. CaO
C. Al2O3
D. Fe2O3
Question 2
Determine the pH of a 0.1 M solution of HCl.
A. 1
B. 2
C. 3
D. 4
Question 3
A sample of a metal (X) is heated in a stream of oxygen gas. The resulting product is a solid (Y). Identify the metal (X) and the solid (Y).
A. Fe, Fe2O3
B. Cu, CuO
C. Zn, ZnO
D. Ag, Ag2O
Question 4
A 25.0 mL sample of 0.100 M HCl is titrated with 0.100 M NaOH. Calculate the pH of the solution after 10.0 mL of NaOH has been added.
A. 2.00
B. 2.50
C. 3.00
D. 3.50
Question 5
A solution of NaOH is added to a solution of HCl. The resulting solution is a salt of which of the following metals?
A. Na
B. Ca
C. Mg
D. Al
Question 6
A 25.0 mL sample of a solution containing 0.100 M CuSO4(aq) is titrated with 0.100 M NaOH(aq). What is the volume of NaOH(aq) required to reach the equivalence point?
A. 25.0 mL
B. 50.0 mL
C. 75.0 mL
D. 100 mL
Question 7
A diagram of a titration setup is shown below. What is the purpose of the burette in this setup?
A. To measure the volume of the titrant
B. To measure the volume of the analyte
C. To mix the titrant and analyte
D. To separate the titrant and analyte
Question 8
The half-life of a radioactive subs\tance is 5.0 years. If the initial activity is 100 Bq, calculate the activity after 10 years.
A. ( 25 ) Bq
B. ( 50 ) Bq
C. ( 75 ) Bq
D. ( 100 ) Bq
Question 9
A 2.5 g sample of a non-metallic oxide is heated in a crucible until it decomposes completely. The mass of the residue is 0.5 g. If the oxide is composed of 60% oxygen by mass, what is the empirical formula of the oxide?
A. MgO
B. CaO
C. Al2O3
D. Fe2O3
Question 10
Determine the rate cons\tant (k) for the reaction: 2NO(g) + O2(g) → 2NO2(g) at 298 K, given that the initial concentrations of NO and O2 are 0.1 M and 0.05 M, respectively, and the rate of reaction is 0.02 M/s.
A. \( 2.5 \times 10^{-3} \) s^{-1}
B. \( 5.0 \times 10^{-3} \) s^{-1}
C. \( 1.0 \times 10^{-2} \) s^{-1}
D. \( 2.0 \times 10^{-2} \) s^{-1}
Question 11
The s\tandard enthalpy of formation of CO2(g) is -393.51 kJ/mol. Calculate the s\tandard enthalpy of combustion of 1.00 mol of C(s) to produce CO2(g).
A. -393.51 kJ/mol
B. -393.51 kJ/mol + 1.00 kJ/mol
C. -393.51 kJ/mol - 1.00 kJ/mol
D. -393.51 kJ/mol + 2.00 kJ/mol
Question 12
A 1.0 M solution of NaOH is prepared by dissolving 40.0 g of NaOH in water to make 1 L of solution. What is the concentration of OH- ions in the solution?
A. 0.01 M
B. 0.1 M
C. 1.0 M
D. 10.0 M
Question 13
A 2.5 g sample of a non-metallic oxide is heated in a crucible until it decomposes completely. The mass of the residue is 0.5 g. If the oxide is composed of 60% oxygen by mass, what is the empirical formula of the oxide?
A. MgO
B. CaO
C. Al2O3
D. Fe2O3
Question 14
The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. Calculate the s\tandard enthalpy of formation of C(s) + O2(g) → CO2(g).
A. -393.5 kJ/mol
B. -393.0 kJ/mol
C. -392.5 kJ/mol
D. -392.0 kJ/mol
Question 15
The reaction between sodium (Na) and chlorine (Cl2) produces sodium chloride (NaCl). If 2.5 g of sodium reacts with 3.0 g of chlorine, calculate the number of moles of sodium chloride produced.
A. ( 0.25 ) mol
B. ( 0.50 ) mol
C. ( 0.75 ) mol
D. ( 1.00 ) mol

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