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POST UTME DELSU 2020 Chemistry | Objective

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Question 1

Determine the number of moles of $\text{O}_2$ produced at $25^\circ\text{C}$ and $1.00\text{ atm}$ when $2.50\text{ g}$ of $\text{KClO}_3$ is decomposed according to the equation $\text{KClO}_3$ s)\rightarrow\text{KCl}\( s \ $+\frac{3}{2}\text{O}_2(g)$.

A. 0.125 mol

Correct B. 0.250 mol

C. 0.500 mol

D. 1.00 mol

Correct Answer: B

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Question 2

A diagram of a galvanic cell is shown below. What is the s\tandard cell potential for the reaction $\text{Zn}(s)+\text{Cu}^{2+}$ aq)\rightarrow\text{Zn}^{2+}\( aq \ $+\text{Cu}(s)$?

A. +1.10 V

Correct B. +1.20 V

C. +1.30 V

D. +1.40 V

Correct Answer: B

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Question 3

A $0.500\text{ M}$ solution of $\text{HCl}$ is mixed with a $0.500\text{ M}$ solution of $\text{NaOH}$. What is the pH of the resulting solution?

A. 1.00

Correct B. 2.00

C. 3.00

D. 4.00

Correct Answer: B

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Question 4

A diagram of a titration setup is shown below. What is the concentration of the $\text{HCl}$ solution?

A. 0.100 M

Correct B. 0.200 M

C. 0.300 M

D. 0.400 M

Correct Answer: B

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Question 5

A $0.500\text{ M}$ solution of $\text{CaCl}_2$ is mixed with a $0.500\text{ M}$ solution of $\text{NaOH}$. What is the resulting solution?

A. $\text{Ca(OH)}_2$

B. $\text{CaCl}_2$

C. $\text{NaCl}$

Correct D. $\text{CaCl}_2$ and $\text{NaCl}$

Correct Answer: D

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Question 6

Determine the number of moles of oxygen gas (O2) produced at STP when 2.5 moles of hydrogen peroxide (H2O2) decompose according to the equation: 2H2O2(l) → 2H2O(l) + O2(g).

Correct A. 1.25 moles

B. 2.5 moles

C. 3.75 moles

D. 5 moles

Correct Answer: A

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Question 7

A 10% solution of sodium chloride (NaCl) is prepared by dissolving 10g of NaCl in 90g of water. What is the molarity of the solution?

Correct A. 0.1 M

B. 0.5 M

C. 1 M

D. 5 M

Correct Answer: A

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Question 8

A sample of a non-metallic element has a mass of 25g. If the density of the element is 5.5g/cm3, what is its volume?

A. 2.27 cm3

Correct B. 4.55 cm3

C. 6.82 cm3

D. 9.09 cm3

Correct Answer: B

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Question 9

A solution containing 10g of glu\cose (C6H12O6) in 100g of water has a boiling point elevation of 0.5°C. What is the molar mass of glu\cose?

A. 180 g/mol

B. 200 g/mol

Correct C. 220 g/mol

D. 240 g/mol

Correct Answer: C

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Question 10

A mixture of 20g of sodium chloride (NaCl) and 30g of calcium chloride (CaCl2) is dissolved in 100g of water. What is the total number of moles of ions produced?

A. 6 moles

B. 8 moles

C. 10 moles

Correct D. 12 moles

Correct Answer: D

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Question 11

Determine the pH of a 0.1 M solution of HCl.

A. 1

B. 2

C. 3

Correct D. 4

Correct Answer: D

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Question 12

A 25 mL sample of 0.5 M H2SO4 is titrated with 1 M NaOH. Calculate the number of moles of H2SO4.

A. 0.05

B. 0.1

Correct C. 0.15

D. 0.2

Correct Answer: C

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Question 13

The rate cons\tant for a first-order reaction is 0.05 min^-1. Calculate the half-life of the reaction.

A. 10

Correct B. 20

C. 30

D. 40

Correct Answer: B

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Question 14

A sample of a gas has a volume of 2 L at 25°C and 1 atm. Calculate the volume of the gas at 50°C and 2 atm.

A. 4

B. 6

Correct C. 8

D. 10

Correct Answer: C

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Question 15

The atomic number of an element is 12. What is the number of protons in the nucleus of an atom of that element?

A. 6

Correct B. 12

C. 18

D. 24

Correct Answer: B

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Question 16

The reaction between chlorine gas and potassium iodide is a classic example of a redox reaction. Write the balanced chemical equation for this reaction, including the states of matter for all reac\tants and products.

A. \text{Cl}_2(g) + 2\text{KI}(s) \rightarrow \text{KCl}(s) + \text{I}_2(g)

Correct B. \text{Cl}_2(g) + 2\text{KI}(s) \rightarrow \text{KCl}(s) + \text{I}_2(s)

C. \text{Cl}_2(s) + 2\text{KI}(s) \rightarrow \text{KCl}(s) + \text{I}_2(s)

D. \text{Cl}_2(g) + 2\text{KI}(g) \rightarrow \text{KCl}(s) + \text{I}_2(s)

Correct Answer: B

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Question 17

A 2.5 M solution of sodium hydroxide is titrated with a 1.0 M solution of hydrochloric acid. If 25 mL of the acid solution is required to reach the equivalence point, what is the volume of the sodium hydroxide solution used?

Correct A. 12.5 mL

B. 25 mL

C. 50 mL

D. 100 mL

Correct Answer: A

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Question 18

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?

Correct A. 12.5 g

B. 25 g

C. 50 g

D. 100 g

Correct Answer: A

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Question 19

A 10 M solution of sulfuric acid is diluted to 1 M. What is the volume of the solution after dilution?

A. 10 L

B. 100 L

Correct C. 1000 L

D. 10000 L

Correct Answer: C

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Question 20

A 5 M solution of sodium carbonate is titrated with a 1 M solution of hydrochloric acid. If 20 mL of the acid solution is required to reach the equivalence point, what is the number of moles of sodium carbonate used?

A. 0.1 mol

Correct B. 0.2 mol

C. 0.5 mol

D. 1 mol

Correct Answer: B

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Question 21

A 2 M solution of potassium permanganate is reduced to manganese dioxide. What is the volume of the solution after reduction?

A. 10 L

B. 100 L

Correct C. 1000 L

D. 10000 L

Correct Answer: C

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Question 22

A 5 M solution of sodium hydroxide is titrated with a 1 M solution of hydrochloric acid. If 25 mL of the acid solution is required to reach the equivalence point, what is the number of moles of sodium hydroxide used?

A. 0.1 mol

Correct B. 0.2 mol

C. 0.5 mol

D. 1 mol

Correct Answer: B

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Question 23

A 10 M solution of sulfuric acid is diluted to 1 M. What is the number of moles of sulfuric acid in the final solution?

A. 0.1 mol

B. 0.2 mol

C. 0.5 mol

D. 1 mol

Correct Answer: VIEW ANSWER

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Question 24

In the reaction of cyclohexane with bromine, the major product is cyclohexyl bromide. However, a minor product is also formed. What is the structure of the minor product?

A. 1-bromocyclohexane

Correct B. cis-1,2-dibromocyclohexane

C. trans-1,2-dibromocyclohexane

D. cis-1,4-dibromocyclohexane

Correct Answer: B

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Question 25

A 0.5 M solution of NaOH is mixed with a 0.5 M solution of HCl. What is the pH of the resulting solution?

Correct A. 7

B. 8

C. 9

D. 10

Correct Answer: A

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