POST UTME LASU 2018 Chemistry | Objective

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Question 1
The rate cons\tant (k) of a first-order reaction is 0.05 min^-1. If the initial concentration of the reac\tant is 0.1 M, what is the concentration of the reac\tant after 10 minutes?
A. 0.01 M
B. 0.05 M
C. 0.1 M
D. 0.2 M
Question 2
The atomic radius of an element is 100 pm. If the element is in the 4th period, what is the value of the principal quantum number (n)?
A. 4
B. 5
C. 6
D. 7
Question 3
Calculate the s\tandard enthalpy of formation of NH3(g) from the following data: ΔHf(NH3(g)) = ?; ΔHf(H2(g)) = -285.8 kJ/mol; ΔHf(N2(g)) = 0 kJ/mol.
A. -46.1 kJ/mol
B. -92.2 kJ/mol
C. -46.1 kJ/mol
D. -92.2 kJ/mol
Question 4
A solution contains 0.100 M NaOH and 0.050 M HCl. What is the pH of the solution after mixing?
A. 1.00
B. 2.00
C. 3.00
D. 4.00
Question 5
The reaction: 2A + B → C + D is a first-order reaction with respect to A. If the initial concentration of A is 0.1 M and the rate cons\tant is 0.05 min^-1, what is the concentration of A after 10 minutes?
A. 0.05 M
B. 0.1 M
C. 0.15 M
D. 0.2 M
Question 6
A 2.5 L flask contains 0.5 mol of an ideal gas at 27°C. Calculate the pressure of the gas u\sing the ideal gas law.
A. 1.01 x 10^5 Pa
B. 2.02 x 10^5 Pa
C. 3.03 x 10^5 Pa
D. 4.04 x 10^5 Pa
Question 7
Calculate the pH of a solution containing 0.1 M HCl and 0.1 M NaOH.
A. 1
B. 2
C. 3
D. 4
Question 8
A 25 mL sample of a solution containing 0.5 M HCl is titrated with 0.5 M NaOH. What is the pH of the solution after the titration?
A. 7
B. 8
C. 9
D. 10
Question 9
The compound C2H4O is a primary alcohol. Draw the structure of its enantiomer.
A. CH3CH(OH)CH3
B. CH3CH(OH)CH2CH3
C. CH3CH2CH(OH)CH3
D. CH3CH2CH2CH(OH)CH3
Question 10
The reaction 2A(g) + B(g) → 2C(g) has a s\tandard enthalpy change of -200 kJ/mol. If 2.5 mol of A and 1.5 mol of B are mixed, calculate the total enthalpy change.
A. -450 kJ
B. -475 kJ
C. -500 kJ
D. -525 kJ
Question 11
A solution of 0.1 M HCl is mixed with a solution of 0.1 M NaOH. What is the pH of the resulting solution?
A. 1
B. 2
C. 3
D. 4
Question 12
A solution contains 0.1 M NaCl. If 10 mL of this solution is diluted to 100 mL, what is the concentration of the solution?
A. 0.01 M
B. 0.05 M
C. 0.1 M
D. 0.2 M
Question 13
A metal M reacts with chlorine gas to form a white solid MX. If 2.50 g of M reacts with 1.50 g of Cl2 to produce 3.25 g of MX, what is the empirical formula of MX?
A. MCl2
B. MCl3
C. MCl4
D. MCl5
Question 14
A solution contains 5 g of glu\cose in 100 g of water. What is the molarity of the solution?
A. 0.1 M
B. 0.5 M
C. 1.0 M
D. 5.0 M
Question 15
The reaction: 2Fe2O3 + 3C → 4Fe + 3CO is a reduction reaction. What is the reducing agent?
A. Fe2O3
B. C
C. Fe
D. CO

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