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UTME 2019 Chemistry | Objective

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Question 1

An increase in temperature causes an increase in the pressure of a gas because there is an increase in the

Correct A. average velocity of the molecules

B. number of collisions between the molecules

C. density of the molecules

D. free mean path between each molecules and the other.

Correct Answer: A

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Question 2

The forces holding naphthalene crystal together can be overcome when naphthalene is heated to a temperature of 354 K resulting in the crystals melting. The forces are known as

A. coulombic

B. ionic

C. covalent

Correct D. vander Waals.

Correct Answer: D

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Question 3

A metallic ion \( \mathrm{X}^{2+} \) with an inert gas structure contains 18 electrons. How many protons are there in this ion?

Correct A. 20

B. 18

C. 16

D. 2

Correct Answer: A

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Question 4

Which of the following physical properties decreases across the Periodic Table?

A. Ionization potential

B. Electron affinity

C. Electronegativity

Correct D. Atomic radius.

Correct Answer: D

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Question 5

What are the possible oxidation numbers for an element if its atomic number is 17 ?

Correct A. -1 and 7

B. -1 and 6

C. -3 and 5

D. -2 and 6

Correct Answer: A

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Question 6

The energy change accompanying the addition of an electron to gaseous atom is called

A. first ionization energy

B. second ionization energy

Correct C. electron affinity

D. electronegativity.

Correct Answer: C

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Question 7

The molar ratio of oxygen to nitrogen in dissolved air is \( 2: 1 \) whereas the ratio is \( 4: 1 \) in atmospheric air because

Correct A. nitrogen is less soluble than oxygen

B. oxygen is heavier than nitrogen

C. nitrogen has a higher partial pressure in air

D. gases are hydrated in water.

Correct Answer: A

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Question 8

The four classes of hydrocarbons are

A. ethane, ethene, ethyne and benzene

Correct B. alkanes, alkenes, alkynes and aromatics

C. alkanes, alkenes, alkynes and benzene

D. methane, ethane, propane and butane.

Correct Answer: B

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Question 9

\( \text{Alkanes} \xrightarrow{400^\circ\text{C} - 700^\circ\text{C}} \) \( \text{ alkanes + hydrogen.} \) \( \\ \text{The above reaction is known as} \)

A. photolysis

Correct B. cracking

C. isomerization

D. reforming.

Correct Answer: B

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Question 10

In the reaction \( \\ 2(\text{C}_{6}\text{H}_{10}\text{O}_{5})_{n} + n\text{H}_{2}\text{O} \xrightarrow{\text{diastase}/60^\circ\text{C}} n\text{C}_{12}\text{H}_{22}\text{O}_{11}, \\ \) diastase is functioning as

A. a dehydrating agent

B. reducing agent

C. an oxidizing agent

Correct D. a catalyst.

Correct Answer: D

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Question 11

Which of the following compounds has the highest boiling point?

Correct A. \( \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OH} \quad \)

B. \( \mathrm{CH}_{3}, \mathrm{CH}, \mathrm{CHO} \)

C. \( \mathrm{CH}, \mathrm{CH}, \mathrm{CH}, \mathrm{CH} \)

D. \( \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OCH}_{2} \mathrm{CH}_{3} \)

Correct Answer: A

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Question 12

If in the graph, 1 dm3 of a saturated solution of KCl is cooled from 800 C to 300 C , the mass of crystals deposited will be \( \\ [\mathrm{~K}=39, \mathrm{Cl}=35.5] \)

A. 7.45 g

B. 14.90 g

C. 74.50 g

Correct D. 49.00 g

Correct Answer: D

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Question 13

Using 50 cm3 of \( 1M \) potassium hydroxide and 100 cm3 of \( 1M \) tetraoxosulphate (VI) acid, calculate the respective volumes in cm3 of base and acid that would be required to produce the maximum amount of potassium tetraoxosulphate (VI).

A. 50.50

B. 25.50

C. 50,25

Correct D. 25,25

Correct Answer: D

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Question 14

A solution of calcium bromide contains 20 g dm3. What is the molarity of the solution with respect to calcium bromide and bromide ions? \( \quad[\mathrm{Ca}=40, \mathrm{Br}=80] \)

A. \( 0.1 \quad \)

Correct B. \( 0.1,0.2 \)

C. \( 0.1,0.05 \)

D. \( 0.05,0.1 \)

Correct Answer: B

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Question 15

The substance ZnO dissolves in sodium hydroxide solution and mineral acid solution to give soluble products in each case. ZnO is therefore referred to as

A. an allotropic oxide

Correct B. an amphoteric oxide

C. a peroxide

D. a dioxide.

Correct Answer: B

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Question 16

An acid and its conjugate base

A. can neutralise each other to form a salt

Correct B. differ only by a proton

C. differ only by the opposite charge they carry

D. are always neutral substances.

Correct Answer: B

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Question 17

Alkanoic acids have low volatility compared with alkanols because they

A. are more polar than alkanols

B. have two oxygen atoms while alkanols have one

C. form hydrogen bonds while alkanols do not

Correct D. form two hydrogen bonds while alkanols form one

Correct Answer: D

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Question 18

The octane number of a fuel whose performance is the same as that of a mixture of 55 g of 2.2, 4trimethylpentane and 45 g of n-heptane is

Correct A. 45

B. 55

C. 80

D. 100

Correct Answer: A

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Question 19

Which of the following is formed when maltose reacts with concentrated tetraoxosulphate (IV) acid?

Correct A. Carbon (IV) oxide

B. Coal tar

C. Charcoal

D. Toxic fumes.

Correct Answer: A

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Question 20

Which of the following compounds represents the polymerization product of ethyne?

Question 21

How many grams of H 2 SO 4 are necessary for the preparation of 0.175 dm 3 of 6.00 MH 2 SO 4 ? \( [\mathrm{S}=32.06 . \mathrm{O}=16.00 . \mathrm{H}=1.001 ] \)

Correct A. 206.0 g

B. 103.0 g

C. 98.1 g

D. 51.5g

Correct Answer: A

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Question 22

Copper (II) tetraoxosulphate (VI) solution is electrolysed using carbon electrodes. Which of the following are produced at the anode and cathode respectively?

Correct A. Copper and oxygen

B. Oxygen and copper

C. Hydrogen and copper

D. Copper and hydrogen

Correct Answer: A

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Question 23

Calculate the mass in kilograms, of magnesium produced by the electrolysis of magnesium (II) chloride in a cell operating for 24 hours at 500 amperes.

Correct A. 2.7

B. 5.4

C. 10.8

D. 21.7

Correct Answer: A

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Question 24

\( \mathrm{MnO}_2 + 2 \mathrm{Cl}+4 \mathrm{H}\rightarrow \mathrm{Mn}_ 2+\mathrm{Cl}_2+2 \mathrm{H}_2 \mathrm{O} \). The changes in oxidation numbers when the manganese, chloride and hydrogen ions react according to the above equation are respectively.

Correct A. 2,2,4

B. -1,-2,4

C. -2,1,0

D. 2.4.0

Correct Answer: A

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Question 25

\( \text{S}_2\text{O}_3^{2-} + \text{I}_2 \to \text{S}_4\text{O}_6^{2-} + 2\text{I}^{-} \). In the reaction, the oxidizing agent is

Correct A. \( \text{S}_2\text{O}_3^{2-} \)

B. \( \text{I}_2 \)

C. \( \text{S}_4\text{O}_6^{2-} \)

D. \( \text{I}^{-} \)

Correct Answer: A

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