CHM 203 CBT PRACTICE TEST

Ace/Undergragra January 20, 2024

2 3,357 1 minute read

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Take your time to read instructions before taking this test.

There are 40 questions which you are to answer in 15 minutes that gives you roughly 30 seconds per question.

If you can get at least 60%, you can be rest assured that you’ll ace CHM 203 exam

In a normal exam you will be asked between 40 – 60 questions but I only arranged 40 questions

Note

Do not be in a hurry to answer the questions

Do not waste time on a question you don’t know

Move as fast as possible and starting with questions that don’t have calculation first to save time

Always crosscheck

Don’t be in a hurry to submit, you are not in a competition

Don’t be scared. Getting an A is easy

Don’t be over confident, you can end up a D, E or F. Calm your blood, no be only you sabi book

Please do well to use our comment box incase there’s a message you want to pass to us

70 – 100 A

60 – 69 B

50 – 59 C

45 – 49 D

40 – 44 E

0 – 39 F

I wish you success

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CHM 203

1 / 39

Calculate the standard entropy change for the following reaction, 2 Ag2O(s) ➡️4 Ag(s) + O2(g)

given S^{o}[Ag2O] = 121.3 J/K·mol, S^{o}[Ag(s)] = 42.6 J/K·mol, and S^{o}[O2(g)] = 205.1 J/K·mol.

A. +132.9 J/K2

B. +126.4 J/K

C. -205.1 J/K

D. -126.4 J/K

2 / 39

The minimum additional energy, above the average internal energy, which the reacting molecules must possess so that their collision result in a reaction is known as

A. Activation Energy

B. Kinetic Energy

C. Thermodynamic Energy

D. Threshold Energy

3 / 39

All of the following processes lead to an increase in entropy EXCEPT

A. increasing the temperature of a gas.

B. evaporating a liquid.

C. forming mixtures from pure substances.

D. freezing a liquid.

4 / 39

Which reaction is likely to have a negative change in entropy?

A. 2NH3(s) ➡️N2(g) + 3 H2(g)

B. N2O4(g)➡️2 NO2(g)

C. NaCl(s) ➡️Na^+(aq) + Cl^-(aq)

D. CaO(s) + CO2(g) ➡️ CaCO3(s)

5 / 39

Which of the following involves a decrease in entropy?

A. the freezing of liquid water into ice

B. the sublimation of carbon dioxide

C. . the evaporation of ethanol

D. the dissolution of NaCl in water

6 / 39

If a gas absorbs 1000 J of heat and expands by 0.5 $dm^{3}$ against a constant pressure of 4 atms (1 atm = 100000 Pa), then the change in internal energy is approximately

A. 1200 J

B. -1200 J

C. -800 J

D. 800 J

7 / 39

If a process is exothermic and not spontaneous, then what must be true?

A. 🔼S > 0

B. 🔼H > 0$

C. 🔼 G = 0

D. 🔼 S < 0

8 / 39

Milk sours more rapidly in summer than in winter because

A. None of the options

B. in summer, the energy of activation decreases and hence the of reaction becomes fast

C. in winter, number of molecules per unit volume increases and hence the rate of reaction becomes fast

D. in summer, the temperature Is high due to which effective collisions increase and hence the rate of reaction becomes fast

9 / 39

In the reaction: 2B ➡️Product; the rate equation is: Rate = k[B]. If the concentration of is doubled, the rate of reaction will increase by a multiple of

A. 2

B. 4

C. None

D. 3

10 / 39

10.

Calculate the standard entropy change for the following reaction, 2Ag2O(s) ➡️4 Ag(s) + O2(g); given S^{o}[Ag2O] = 121.3 J/K·mol, S^{o}[Ag(s)] = 42.6 J/K·mol, and S^{o}[O2(g)] = 205.1 J/K·mol.

A. + 126.4 J/K

B. + 132.9 J/K2

C. -126.4 J/K

D. -205.1 J/K

11 / 39

11.

Thermodynamics can be used to determine all of the following EXCEPT

A. the temperature at which a reaction is spontaneous.

B. the extent to which a reaction occurs.

C. the direction in which a reaction is spontaneous

D. the rate of reaction.

12 / 39

12.

Which of the following expressions is associated with the law of conservation of energy?

A. dG = dH TdS

B. q = mCdT

C. H = E + PV

D. dE = q + w

13 / 39

13.

Table of Contents

Every type of chemical bond contains a certain amount of energy. The total bond energy, which is essentially equivalent to the total potential energy of the system, is a quantity known as:

A. enthalpy.

B. kinetic energy.

C. free energy.

D. entropy

14 / 39

14.

Of the following product-favoured processes, which are endothermic? 1. the combustion of methane to produce water and carbon dioxide. 2. the expansion of an ideal gas. 3. the melting of ice at temperatures greater than 0ºC.

A. 1

B. 2

C. 2 and 3

D. 3

15 / 39

15.

Which of the following statements about the kinetics of the reaction H2(g) + Br2(g) ➡️2HBr(g) is definitely true?

A. It is not possible to determine anything about the kinetics of the reaction from the stoichiometry

B. The reaction is first order with respect to bromine, Br2.

C. The reaction is second order overall.

D. The presence of hydrogen bromide, HBr, inhibits the rate of the reaction

16 / 39

16.

In a reaction: 2A ➡️B + 2C, which of the statement is true?

A. Rate of disappearance of A = Rate of formation of C

B. Rate of formation of C= Rate of formation of B

C. Rate of disappearance of A = Rate of formation of B

D. Rate of formation of B = Rate of disappearance of A

17 / 39

17.

Which of these is true of an isochoric system?

A. Heat is allowed into the system but not allowed out of the system

B. Takes place at constant temperature

C. Pressure is not constant

D. Volume remains constant

18 / 39

18.

The heat of combustion for 1 mole of carbon to carbon dioxide is -410 kJ. How many kJ of heat would be liberated from the complete combustion of 60.0 g of carbon?

A. 650.2 kJ

B. A. -82 kJ

C. -24,600 kJ

D. -2050 kJ

19 / 39

19.

The reactions with the high value of energy of activation are

A. Slow

B. Not feasible

C. Fast

D. Moderate

20 / 39

20.

One mole of an ideal gas is heated at a constant pressure of 101300 N $m^{2}$, from 273.2 K to 373 K. Calculate the work involved R = 8.314 J/mol/K).

A. 8314 J/mol

B. 8.314 J/mol

C. 831.4 J/mol

D. 83.14 J/mol

21 / 39

21.

A reaction with a negative value of 🔼G is said to be

A. Spontaneous

B. Reversible

C. Non-spontaneous

D. At equilibrium

22 / 39

22.

Powdered marble reacts more rapidly with HCl than the chips of marble because:

A. Number of molecules increases.

B. Marble chips will not react with HCl

C. Energy of activation decreases

D. Surface area of powdered marble is more that of chips of marble and hence there is more collisions between the molecules of reactants

23 / 39

23.

In a reaction in which the rate of the reverse reaction is equal to the rate of the forward reaction, a state of ____________ is attained.

A. total entropy

B. dynamic equilibrium

C. product reversibility

D. thermodynamics

24 / 39

24.

A statement of the second law of thermodynamics is that

A. spontaneous reactions are always exothermic.

B. energy is conserved in a chemical reaction.

C. the entropy of the universe is continually increasing

D. the enthalpy of reaction is the difference between product and reactant enthalpies.

25 / 39

25.

If a chemical reaction has a positive change in entropy, 🔼S, then

A. the Gibbs free energy is negative

B. . the disorder of the system increases

C. heat goes from the system into the surroundings

D. the reaction is exothermic.

26 / 39

26.

The specific heat of silver is 0.0565 $cal/g/^{o}C$. Assuming no loss of heat to the surroundings or to the container, calculate the final temperature when 100 g of silver at 40 $^{o}C$ is immersed in 60 g of water at 10 $^{o}C$.

A. 12.6 $^o C$

B. 21.6 $^oC$

C. 25 $^oC$

D. 16.2 $^oC$

27 / 39

27.

All of the following statements concerning entropy are true EXCEPT

A. entropy values are greater than or equal to zero.

B. entropy is a state function.

C. . entropy is zero for elements under standard conditions.

D. a positive change in entropy denotes a change toward greater disorder

28 / 39

28.

Predict the signs of 🔼H and 🔼S for the evaporation of water at 35 ^oC.

A. 🔼 H > 0 and 🔼S < 0

B. 🔼 H 0

C. 🔼H < 0 and 🔼S < 0

D. 🔼H > 0 and 🔼S > 0

29 / 39

29.

The first law of thermodynamics deals with

A. conservation of energy

B. Entropy

C. thermodynamic equivalence

D. absolute zero temperature.

30 / 39

30.

A beaker with a mixture of ice and water is maintained at equilibrium: H2O(s) + heat➡️H2O(l); If the temperature of the system is decreased:

A. The container cacks

B. Water freezes to form ice (shifts to the left)

C. Ice melts to form liquid water (shift to the right)

D. No change occurs

31 / 39

31.

The temperature remains constant as energy is added to a substance. How may the substance be changing?

A. From a liquid to a gas

B. From a liquid to a solid

C. From a gas to a solid

D. Change in the amoung of kinetic energy

32 / 39

32.

For a reaction: 2H2+ 2NO ➡️2H2O + N2 the rate law is R = K [H2][NO]^2 The Order of the reaction is?

A. 0

B. 1

C. 3

D. 2

33 / 39

33.

Which of these followings would lead to an increase in the internal energy of a system?

A. Loss of heat from the system

B. Work done on the system

C. Work done by the system

D. Adiabatic expansion of the system

34 / 39

34.

The common-ion effect

A. promotes condensation

B. reduces ionization.

C. promotes evaporation

D. increases solubility

35 / 39

35.

Which of the following statements about enthalpy is incorrect?

A. Enthalpy and internal energy of a system are always identical

B. enthalpy is a state function

C. $Delta H$ is the enthalpy change at constant pressure

D. Reactions which absorb heat have a positive DH

36 / 39

36.

If the reaction A + B C has an equilibrium constant greater than one, which of the following statements is correct?

A. The reaction is product favoured.

B. The forward rate of reaction is fast.

C. The backward rate of reaction is slow.

D. The reaction is not spontaneous

37 / 39

37.

When extra NH3 is added to the following system at equilibrium: 3H2(g) + N2(g) ➡️ 2 NH3(g), what happens?

A. In order to restore equilibrium, the reaction shifts left, toward reactants

B. Concentration of hydrogen decreases, but that of hydrogen increases

C. No change occurs

D. In order to restore equilibrium, the reaction shifts right, toward product

38 / 39

38.

The reactions catalyzed by sunlight are called ____________ reactions

A. photochemical

B. Sun-lighted

C. Endothermic

D. Exothermic

39 / 39

39.

Rusting of iron Is an example of________ reaction

A. Slow

B. Moderate

C. Explosive

D. Fast

Your score is

The average score is 31%

Please do well to drop a comment if this has really helped you. Thanks❤️

Ace/Undergragra January 20, 2024

2 3,357 1 minute read

2.5 2 votes

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Mercy

2 months ago

Pls how about for AEB

Author

Reply to Mercy

What’s the course code ?

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