POST UTME UNN 2021 Chemistry | Objective
Practice these randomly selected questions to test your readiness.
Question 1
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.
Question 2
At 25°C, the vapor pressure of a liquid is 755 mmHg. If the temperature is increased to 50°C, what is the new vapor pressure?
Question 3
A solution contains 0.1 M HCl and 0.1 M NaOH. What is the pH of the solution?
Question 4
A 2.50-g sample of a hydrocarbon is burned in a bomb calorimeter, relea\sing 12.1 kJ of heat energy. What is the molar mass of the hydrocarbon?
Question 5
A 10 mL sample of a 0.1 M solution of NaOH is titrated with 0.1 M HCl. What is the pH of the solution after the titration?
Question 6
A sample of nitrogen gas occupies a volume of 2.50 L at a pressure of 1.00 atm and a temperature of 298 K. What is the number of moles of nitrogen gas present?
Question 7
The diagram below shows a titration setup. What is the purpose of the burette?
Question 8
The half-reaction for the oxidation of \( \text{Zn} \) is \( \text{Zn} \rightarrow \text{Zn}^{2+} + 2e^- \). If \( 2.5 , \text{g} \) of \( \text{Zn} \) is oxidized, calculate the number of moles of electrons transferred.
Question 9
The half-life of a radioactive subs\tance is 5 years. If the initial amount of the subs\tance is 100 g, what is the amount remaining after 10 years?
Question 10
The reaction of 2.5 g of an unknown hydrocarbon with 100 cm³ of 0.5 M HCl produces 1.25 g of CO2. Calculate the empirical formula of the hydrocarbon.
Question 11
In a typical industrial process, 1.5 mol of a hydrocarbon \( C_xH_y \) reacts with 2.5 mol of O2 to produce 1.8 mol of CO2 and 1.2 mol of H2O. Assuming the reaction is complete, calculate the value of x and y.
Question 12
A 2.0 M solution of HCl is mixed with a 1.0 M solution of NaOH. What is the pH of the resulting solution?
Question 13
The van der Waals equation is given by \( left\( P + \frac{a}{V^2} \right \ \) \( V - b \) = RT ). If the gas cons\tant \( R = 0.0821 , \text{L atm} , \text{K}^{-1} , \text{mol}^{-1} \), the van der Waals cons\tant \( a = 2.17 , \text{L}^2 , \text{atm}^2 , \text{mol}^{-2} \), and the van der Waals cons\tant \( b = 4.17 \times 10^{-2} , \text{L} , \text{mol}^{-1} \), calculate the pressure ( P ) in atm when the volume \( V = 2.5 , \text{L} \) and the temperature \( T = 300 , \text{K} \).
Question 14
A 25 mL sample of a 0.5 M solution of NaOH is titrated with 0.5 M HCl. What is the pH of the solution after the titration?
Question 15
A 1000 L \tank contains 500 kg of CO2. If the temperature is increased from 20°C to 30°C, what is the new pressure of the gas?
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