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POST UTME LAUTECH 2019 Chemistry | Objective

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Question 1

A 2.5 M solution of NaOH is mixed with a 2.5 M solution of HCl. What is the resulting pH of the solution?

A. 7

Correct B. 9

C. 10

D. 12

Correct Answer: B

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Question 2

A metal (M) reacts with oxygen to form a basic oxide. The reaction is as follows: 4M + 3O2 → 2M2O3. What is the oxidation state of M in M2O3?

A. 2

B. 3

Correct C. 4

D. 5

Correct Answer: C

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Question 3

A 1.0 M solution of HCl is mixed with a 1.0 M solution of NaOH. What is the resulting concentration of HCl?

Correct A. 0.5 M

B. 1.0 M

C. 1.5 M

D. 2.0 M

Correct Answer: A

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Question 4

A metal (M) reacts with oxygen to form a basic oxide. The reaction is as follows: 4M + 3O2 → 2M2O3. What is the mass of 2.5 g of M2O3?

A. 5.0 g

B. 5.5 g

Correct C. 6.0 g

D. 6.5 g

Correct Answer: C

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Question 5

A 2.5 M solution of NaOH is mixed with a 2.5 M solution of HCl. What is the resulting pH of the solution?

A. 7

Correct B. 9

C. 10

D. 12

Correct Answer: B

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Question 6

Determine the rate cons\tant (k) for the reaction: A → B + C, given that the initial concentration of A is 0.5 M, and after 10 minutes, the concentration of A has decreased to 0.2 M. The rate cons\tant is related to the half-life $ t1/2 $ by the equation: k = ln(2)/t1/2.

Correct A. 0.05 min^-1

B. 0.1 min^-1

C. 0.2 min^-1

D. 0.5 min^-1

Correct Answer: A

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Question 7

A 0.1 M solution of HCl is titrated with 0.1 M NaOH. At the equivalence point, the pH of the solution is 7. Calculate the volume of NaOH required to reach the equivalence point.

A. 10 mL

Correct B. 20 mL

C. 30 mL

D. 40 mL

Correct Answer: B

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Question 8

The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. Calculate the s\tandard enthalpy of formation of CH4(g) if the s\tandard enthalpy of formation of C(s) is -717.1 kJ/mol and the s\tandard enthalpy of formation of H2(g) is 0 kJ/mol.

A. -74.8 kJ/mol

B. -74.9 kJ/mol

Correct C. -75.0 kJ/mol

D. -75.1 kJ/mol

Correct Answer: C

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Question 9

A 1.0 M solution of glu\cose (C6H12O6) is placed in a 1.0 L flask and allowed to reach equilibrium with the atmosphere. If the partial pressure of CO2 is 0.1 atm, calculate the concentration of glu\cose remaining in the solution.

A. 0.5 M

Correct B. 0.6 M

C. 0.7 M

D. 0.8 M

Correct Answer: B

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Question 10

A 0.1 M solution of HCl is titrated with 0.1 M NaOH. At the equivalence point, the pH of the solution is 7. Calculate the volume of NaOH required to reach the equivalence point.

A. 10 mL

Correct B. 20 mL

C. 30 mL

D. 40 mL

Correct Answer: B

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Question 11

Determine the number of moles of oxygen gas (O2) produced at 25°C and 1 atm when 2.5 g of potassium chlorate (KClO3) decomposes according to the equation: 2KClO3(s) → 2KCl(s) + 3O2(g).

A. 0.125 mol

Correct B. 0.25 mol

C. 0.5 mol

D. 1.0 mol

Correct Answer: B

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Question 12

A 2.0 L flask contains 0.50 mol of an ideal gas at 25°C. If the gas is heated to 50°C at cons\tant volume, what is the new pressure?

A. 1.5 atm

B. 2.0 atm

Correct C. 2.5 atm

D. 3.0 atm

Correct Answer: C

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Question 13

A solution contains 0.10 M glu\cose (C6H12O6) and 0.20 M fructose (C6H12O6). What is the total molarity of the solution?

A. 0.10 M

B. 0.20 M

Correct C. 0.30 M

D. 0.40 M

Correct Answer: C

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Question 14

A 10.0 g sample of a polymer is dissolved in 100.0 mL of a solvent. If the polymer has a molecular weight of 50,000 g/mol, what is the concentration of the solution in g/L?

A. 0.05 g/L

B. 0.10 g/L

Correct C. 0.20 g/L

D. 0.50 g/L

Correct Answer: C

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Question 15

A 2.0 L flask contains 0.50 mol of an ideal gas at 25°C. If the gas is cooled to 0°C at cons\tant pressure, what is the new volume?

Correct A. 1.0 L

B. 1.5 L

C. 2.0 L

D. 2.5 L

Correct Answer: A

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Question 16

Determine the number of moles of $\text{O}_2$ produced when 2.5 moles of $\text{Ca}$ $\text{NO}_3 $_2$ are decomposed at cons\tant pressure and temperature.

Correct A. 1.25

B. 2.5

C. 3.75

D. 5.0

Correct Answer: A

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Question 17

A 0.5 M solution of $\text{NaOH}$ is mixed with a 0.5 M solution of $\text{HCl}$. What is the pH of the resulting solution?

A. 1

B. 2

Correct C. 7

D. 14

Correct Answer: C

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Question 18

A metal (X) reacts with $\text{HCl}$ to produce $\text{H}_2$ gas. The reaction is as follows: $\text{X} + 2\text{HCl} \rightarrow \text{XCl}_2 + \text{H}_2$. If 2.5 moles of $\text{HCl}$ are used, what is the number of moles of $\text{H}_2$ produced?

A. 0.5

Correct B. 1.0

C. 1.5

D. 2.0

Correct Answer: B

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Question 19

A solution containing 0.1 M $\text{Fe}^{2+}$ ions is mixed with a solution containing 0.1 M $\text{SCN}^-$ ions. What is the concentration of the complex ion $\text{[Fe(SCN)]}^+$ formed?

A. 0.01

Correct B. 0.05

C. 0.1

D. 0.2

Correct Answer: B

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Question 20

A 2.0 M solution of $\text{H}_2SO_4$ is mixed with a 2.0 M solution of $\text{NaOH}$. What is the pH of the resulting solution?

A. 1

B. 2

Correct C. 7

D. 14

Correct Answer: C

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Question 21

The atomic radius of an element is 100 pm. If the element is in the 4th period, what is the expected value of its atomic radius in the 5th period?

A. 120 pm

B. 130 pm

Correct C. 140 pm

D. 150 pm

Correct Answer: C

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Question 22

A 2.5 M solution of HCl is prepared by dissolving 25 g of HCl in water to make 1 L of solution. What is the molarity of the solution?

A. 2.0 M

Correct B. 2.5 M

C. 3.0 M

D. 3.5 M

Correct Answer: B

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Question 23

A metal (X) reacts with dilute HCl to produce a gas that turns lime water milky. The metal is likely to be

Correct A. Zn

B. Fe

C. Cu

D. Ag

Correct Answer: A

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Question 24

A solution contains 0.1 M HCl and 0.2 M NaOH. What is the pH of the solution?

A. 1

Correct B. 2

C. 3

D. 4

Correct Answer: B

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Question 25

A 10% solution of NaOH is prepared by dissolving 10 g of NaOH in water to make 100 mL of solution. What is the molarity of the solution?

A. 0.1 M

B. 0.5 M

Correct C. 1.0 M

D. 2.0 M

Correct Answer: C

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