POST UTME ABU 2019 Chemistry | Objective
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Question 1
A 2.5 L flask contains 0.5 mol of an ideal gas at 27°C. Calculate the pressure of the gas in atm.
Question 2
The atomic radius (r) of an atom is given by the equation: r = \( n^2 / Z \) * a0, where n is the principal quantum number, Z is the atomic number, and a0 is the Bohr radius. If the atomic number is 6, the principal quantum number is 2, and the Bohr radius is 5.29 x 10^\( -11 \) m, calculate the atomic radius (r).
Question 3
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 hours is 0.05 M. The rate cons\tant is related to the half-life \( t1/2 \) of the reaction by the equation: k = ln(2) / t1/2.
Question 4
A solution of 2.0 g of sodium chloride (NaCl) in 100 mL of water has a boiling point elevation of 0.50°C. What is the molar mass of NaCl?
Question 5
The equilibrium cons\tant (K) for a reaction is given by the equation: K = [A]^2 / [B]. If the concentration of A is 1.0 x 10^\( -3 \) M and the concentration of B is 1.0 x 10^\( -4 \) M, calculate the equilibrium cons\tant (K).
Question 6
A 1.00 g sample of a metal is heated in a crucible until it decomposes completely. The mass of the metal oxide obtained is 1.50 g. What is the percentage of oxygen in the original sample?
Question 7
A sample of nitrogen gas at 25°C and 1 atm is heated to 50°C. What is the new volume of the gas?
Question 8
A sample of hydrogen gas at 25°C and 1 atm is mixed with a sample of oxygen gas at 25°C and 1 atm. What is the resulting product?
Question 9
What is the term for the movement of molecules from an area of high concentration to an area of low concentration?
Question 10
A polymer has a molecular weight of 50000 g/mol and a degree of polymerization (DP) of 200. Calculate the molar mass of the repeating unit \( M_r \) of the polymer.
Question 11
The bond length (d) of a diatomic molecule is given by the equation: d = \( n^2 / Z \) * a0, where n is the principal quantum number, Z is the atomic number, and a0 is the Bohr radius. If the atomic number is 8, the principal quantum number is 3, and the Bohr radius is 5.29 x 10^\( -11 \) m, calculate the bond length (d).
Question 12
A 2.5 L flask contains 0.5 mol of an ideal gas at 27°C. Calculate the pressure of the gas in atm.
Question 13
What is the term for the process by which a solid dissolves in a liquid?
Question 14
The half-life \( t1/2 \) of a radioactive subs\tance is given by the equation: t1/2 = ln(2) * \sigma / \( \mu * c^2 \), where \sigma is the cross-sectional area, \mu is the mass density, and c is the speed of light. If the half-life is 10 years, the cross-sectional area is 1.0 x 10^\( -20 \) m^2, the mass density is 1.0 x 10^3 kg/m^3, and the speed of light is 3.0 x 10^8 m/s, calculate the mass density \( \mu \).
Question 15
The reaction of an alkane with chlorine in the presence of light produces a dichloroalkane. What is the major product of this reaction?
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