POST UTME RHEMA UNIVERSITY 2021 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
A 2.5 g sample of a compound containing only carbon and hydrogen is burned in a combustion apparatus. The volume of carbon dioxide produced is 2.5 liters at 25°C and 1 atm. What is the empirical formula of the compound?
A. CH4
B. C2H6
C. C3H8
D. C4H10
Question 2
A 2.5 M solution of HCl is titrated with 1.0 M NaOH. Calculate the pH of the solution after 25 mL of NaOH has been added.
A. ( 2.0 )
B. ( 2.5 )
C. ( 3.0 )
D. ( 3.5 )
Question 3
A solution contains 0.100 M sodium chloride (NaCl) and 0.0500 M sodium sulfate (Na2SO4). What is the concentration of chloride ions \( Cl- \) in the solution?
A. 0.0500 M
B. 0.0750 M
C. 0.100 M
D. 0.125 M
Question 4
A 1.00 L flask contains 0.500 mol of CO2 at 298 K. If 0.500 mol of O2 is added to the flask, what is the partial pressure of CO2 in the resulting mixture?
A. 0.500 atm
B. 0.500 atm
C. 0.500 atm
D. 0.500 atm
Question 5
A sample of nitrogen gas occupies a volume of 2.50 L at a pressure of 1.50 atm and a temperature of 298 K. What is the new volume of the gas if the pressure is increased to 3.00 atm and the temperature is decreased to 273 K?
A. 1.00 L
B. 1.50 L
C. 2.00 L
D. 2.50 L
Question 6
A sample of gas occupies a volume of 2.5 L at a pressure of 3.0 atm. What is the pressure of the gas if its volume is reduced to 1.0 L?
A. 6.0 atm
B. 3.0 atm
C. 1.5 atm
D. 0.5 atm
Question 7
A 10.0 mL sample of 0.100 M H2SO4 is added to a 20.0 mL sample of 0.0500 M NaOH. What is the concentration of the resulting solution?
A. 0.0500 M
B. 0.100 M
C. 0.150 M
D. 0.200 M
Question 8
A sample of a metal M has a mass of 25 g. If the density of the metal is 8.5 g/cm3, what is the volume of the metal?
A. 2.9 cm3
B. 3.0 cm3
C. 3.1 cm3
D. 3.2 cm3
Question 9
Determine the number of moles of electrons transferred during the electrolysis of 2.5 L of water at 25°C, given that the cell potential is 1.23 V and the current is 0.5 A.
A. 0.5 mol
B. 1.0 mol
C. 1.5 mol
D. 2.0 mol
Question 10
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 C6H12O6(s) at 298 K.
A. \( -2800 , \text{kJ/mol} \)
B. \( -2900 , \text{kJ/mol} \)
C. \( -3000 , \text{kJ/mol} \)
D. \( -3100 , \text{kJ/mol} \)
Question 11
A 2.5 g sample of a compound containing only carbon and hydrogen is burned in a combustion apparatus. The volume of carbon dioxide produced is 2.5 liters at 25°C and 1 atm. What is the empirical formula of the compound?
A. CH4
B. C2H6
C. C3H8
D. C4H10
Question 12
What is the major product of the reaction between 2-methylpropane and chlorine?
A. 2-chloro-2-methylpropane
B. 2,2-dichloro-2-methylpropane
C. 2-chloro-2-methyl-1-propane
D. 2-chloro-2-methyl-2-propane
Question 13
A mixture of 2.0 g of benzene and 3.0 g of toluene is heated to produce a \single product. What is the empirical formula of the product?
A. C6H6
B. C7H8
C. C8H10
D. C9H12
Question 14
A metal M reacts with chlorine gas to form a white solid product. The reaction is as follows: M + Cl2 → MX2. If 2.5 g of M is reacted with 1.5 g of Cl2, what is the limiting reac\tant?
A. M
B. Cl2
C. MX2
D. Neither M nor Cl2 is the limiting reac\tant.
Question 15
The energy change associated with the formation of a mole of water vapor at 100°C and 1 atm is -40.7 kJ/mol. What is the s\tandard enthalpy of vaporization of water at this temperature?
A. 40.7 kJ/mol
B. -40.7 kJ/mol
C. 80.7 kJ/mol
D. -80.7 kJ/mol

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