Home CBT TEST CHM 203 CBT PRACTICE TEST

CHM 203 CBT PRACTICE TEST

Phil

January 20, 2024

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

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

A. CaO(s) + CO2(g) ➡️ CaCO3(s)

B. N2O4(g)➡️2 NO2(g)

C. 2NH3(s) ➡️N2(g) + 3 H2(g)

D. NaCl(s) ➡️Na^+(aq) + Cl^-(aq)

2 / 39

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

A. 🔼 G = 0

B. 🔼H > 0$

C. 🔼S > 0

D. 🔼 S < 0

3 / 39

Which of the following involves a decrease in entropy?

A. the sublimation of carbon dioxide

B. the freezing of liquid water into ice

C. the dissolution of NaCl in water

D. . the evaporation of ethanol

4 / 39

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. 831.4 J/mol

B. 8314 J/mol

C. 8.314 J/mol

D. 83.14 J/mol

5 / 39

The first law of thermodynamics deals with

A. absolute zero temperature.

B. thermodynamic equivalence

C. Entropy

D. conservation of energy

6 / 39

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

A. The forward rate of reaction is fast.

B. The reaction is not spontaneous

C. The reaction is product favoured.

D. The backward rate of reaction is slow.

7 / 39

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. -2050 kJ

D. -24,600 kJ

8 / 39

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. 16.2 $^oC$

B. 25 $^oC$

C. 12.6 $^o C$

D. 21.6 $^oC$

9 / 39

Which of the following statements about enthalpy is incorrect?

A. Reactions which absorb heat have a positive DH

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

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

D. enthalpy is a state function

10 / 39

10.

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

A. At equilibrium

B. Reversible

C. Non-spontaneous

D. Spontaneous

11 / 39

11.

Rusting of iron Is an example of________ reaction

A. Explosive

B. Fast

C. Moderate

D. Slow

12 / 39

12.

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

13 / 39

13.

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 right, toward product

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

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

D. No change occurs

14 / 39

14.

Table of Contents

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

A. forming mixtures from pure substances.

B. increasing the temperature of a gas.

C. evaporating a liquid.

D. freezing a liquid.

15 / 39

15.

Milk sours more rapidly in summer than in winter because

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

B. None of the options

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

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

16 / 39

16.

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. 3

B. 4

C. 2

D. None

17 / 39

17.

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

B. No change occurs

C. The container cacks

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

18 / 39

18.

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

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

B. Energy of activation decreases

C. Marble chips will not react with HCl

D. Number of molecules increases.

19 / 39

19.

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

A. dE = q + w

B. dG = dH TdS

C. q = mCdT

D. H = E + PV

20 / 39

20.

The reactions catalyzed by sunlight are called ____________ reactions

A. Endothermic

B. Exothermic

C. Sun-lighted

D. photochemical

21 / 39

21.

Which of these is true of an isochoric system?

A. Pressure is not constant

B. Volume remains constant

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

D. Takes place at constant temperature

22 / 39

22.

All of the following statements concerning entropy are true EXCEPT

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

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

C. entropy is a state function.

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

23 / 39

23.

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

24 / 39

24.

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. +126.4 J/K

B. -205.1 J/K

C. -126.4 J/K

D. +132.9 J/K2

25 / 39

25.

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 gas to a solid

C. Change in the amoung of kinetic energy

D. From a liquid to a solid

26 / 39

26.

The reactions with the high value of energy of activation are

A. Slow

B. Fast

C. Moderate

D. Not feasible

27 / 39

27.

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

A. heat goes from the system into the surroundings

B. . the disorder of the system increases

C. the Gibbs free energy is negative

D. the reaction is exothermic.

28 / 39

28.

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. 800 J

C. -800 J

D. -1200 J

29 / 39

29.

The common-ion effect

A. promotes condensation

B. increases solubility

C. reduces ionization.

D. promotes evaporation

30 / 39

30.

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. dynamic equilibrium

B. total entropy

C. product reversibility

D. thermodynamics

31 / 39

31.

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. free energy.

C. kinetic energy.

D. entropy

32 / 39

32.

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. Thermodynamic Energy

B. Threshold Energy

C. Kinetic Energy

D. Activation Energy

33 / 39

33.

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

A. Work done on the system

B. Work done by the system

C. Adiabatic expansion of the system

D. Loss of heat from the system

34 / 39

34.

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. 2 and 3

B. 1

C. 3

D. 2

35 / 39

35.

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

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

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

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

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

36 / 39

36.

A statement of the second law of thermodynamics is that

A. the entropy of the universe is continually increasing

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

C. spontaneous reactions are always exothermic.

D. energy is conserved in a chemical reaction.

37 / 39

37.

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

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

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

C. The reaction is second order overall.

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

38 / 39

38.

Thermodynamics can be used to determine all of the following EXCEPT

A. the extent to which a reaction occurs.

B. the rate of reaction.

C. the temperature at which a reaction is spontaneous.

D. the direction in which a reaction is spontaneous

39 / 39

39.

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