POST UTME UNILAG 2021 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
A sample of a compound containing only carbon and hydrogen is found to have a mass of 24.3 g and a mass of 3.2 g of hydrogen. What is the empirical formula of the compound?
A. CH
B. C2H2
C. C2H4
D. C3H6
Question 2
A diagram of a titration setup is shown below. If 25.0 mL of 0.100 M NaOH is required to reach the equivalence point, what is the concentration of the HCl solution?
A. 0.0500 M
B. 0.100 M
C. 0.200 M
D. 0.500 M
Question 3
A metal M reacts with chlorine gas to form a compound MCl2. The molar mass of MCl2 is 142 g/mol. What is the molar mass of M?
A. ( 56.0 ) g/mol
B. ( 58.0 ) g/mol
C. ( 60.0 ) g/mol
D. ( 62.0 ) g/mol
Question 4
A 0.1 M solution of NaOH is titrated with 0.1 M HCl. What is the pH of the solution after the equivalence point?
A. ( 7.0 )
B. ( 8.0 )
C. ( 9.0 )
D. ( 10.0 )
Question 5
At 273 K, the root mean square speed of a gas is 200 m/s. What is the mass of a molecule of the gas?
A. \( 2.5 \times 10^{-25} \) kg
B. \( 5.0 \times 10^{-25} \) kg
C. \( 1.0 \times 10^{-24} \) kg
D. \( 2.0 \times 10^{-24} \) kg
Question 6
A 2.0 L flask contains 0.5 mol of a gas at 300 K. What is the pressure of the gas?
A. \( 2.5 \times 10^5 \) Pa
B. \( 5.0 \times 10^5 \) Pa
C. \( 7.5 \times 10^5 \) Pa
D. \( 1.0 \times 10^6 \) Pa
Question 7
A sample of a gas has a volume of 2.50 L at a temperature of 298 K and a pressure of 1.00 atm. What is the volume of the gas at a temperature of 373 K and a pressure of 2.00 atm?
A. 1.25 L
B. 2.50 L
C. 3.75 L
D. 5.00 L
Question 8
A diagram of a simple black and white chemistry apparatus showing a titration setup is shown below. If 25.0 mL of 0.100 M NaOH is required to reach the equivalence point, what is the concentration of the HCl solution?
A. 0.0500 M
B. 0.100 M
C. 0.200 M
D. 0.500 M
Question 9
Determine the number of moles of oxygen gas (O2) required to completely combust 2.5 moles of methane gas (CH4) according to the balanced equation: CH4 + 2O2 → CO2 + 2H2O.
A. 1.25 moles
B. 2.5 moles
C. 5 moles
D. 10 moles
Question 10
A solution contains 0.1 M HCl and 0.2 M NaOH. What is the pH of the solution after mixing?
A. ( 1.0 )
B. ( 2.0 )
C. ( 3.0 )
D. ( 4.0 )

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