Thermo-Chemistry Online Mcqs Test

Mustansar KhanLast Updated: October 14, 2025

Important Thermo Chemistry Question and Answer

Total Questions:	108
Time Allowed:	60 Minutes
Total Marks:	108
How to Attempt Test:	Please choose the right Option in MCQ-type question.
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Thermo Chemistry Practice Test Online With Explanation

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Page 1 of 5

Chemistry

1. In endothermic reactions, the heat content of the

Both a and b

Reactants and products are equal

Products is more than that of reactants

Reactants is more than that of products

2. For a system in equilibrium, ∆ G = 0, under conditions of constant

Temperature and pressure

Pressure and volume

Energy and volume

Temperature and volume

3. A macroscopic property of a system which describes the initial and final state of the system is called

Physical property

Energy of the system

State function

Chemical property

4. For a reaction to occur spontaneously

∆ H must be positive

∆ H must be unity

∆ H must be negative

∆ H must be zero

5. Which of the following units represents largest amount of energy?

Calorie

Erg

Joule

Electron vol

6. In thermodynamics which one of the following is not an intensive property?

Pressure

Density

Temperature

Volume

7. Total energy of a system is

P.E + heat energy

P.E + K.E

K.E + heat energy

P.E + mechanical energy

8. The branch of chemistry which deals with thermal energy change in chemical reaction is called

Thermochemistry

Mechanics

Chemical kinetics

Thermodynamics

9. For a given process, the heat changes at constant pressure (q_p) and at constant volume (q_v) are related to each other as:

10. The net change in energy in a chemical reaction is same whether it takes place directly or indirectly is

Henry’s law

Hess’s law

Charles’s law

Graham’s law

11. The enthalpies of combustion of carbon and carbon monoxide are -383.5 and -283 kJ mol¯¹ respectively. The enthalpy of formation of carbon monoxide per mole is

110.5 kJ

676.5 kJ

-676.5 kJ

-110.5 kJ

12. The branch of science which deals with energy transformation is known as

Thermodynamics

Photochemistry

Thermochemistry

Kinetics

13. One of the statement about Born Haber cycle is correct. Which is that statement?

Born Haber cycle is different from Hess’s law

The lattice energy of the crystalline substances can be calculated easily

The energy change in a cyclic process is not zero

Heat of formation of the product and lattice energy of the substance can be calculated simultaneously

14. The enthalpy of formation of carbon monoxide will be

2x – y

2x – y/2

Y – 2x

Y – 2x/2

15. The heats evolved in combustion of rhombic and monoclinic sulphur are -70960 and -71030 cal mol¯¹ respectively. What will be heat of conversion of rhombic sulphur to monoclinic?

+70 calories

70960 calories

71030 calories

-70 calories

16. An adiabatic expansion of an ideal gas always has

Decrease in temperature

∆H = 0

W = 0

Q = 0

17. The law of Lavoisier and Laplace illustrates

The principle of conservation of energy

Equivalence of mechanical and thermal energy

Equivalent of mechanical and chemical energy

The principle of conservation of matter

18. A material or a collection of materials which is under study is called

System

Surrounding

Any substance

State function

19. Calorie is equivalent to

4.184 J

418.4 J

41.84 J

0.4184 J

20. Pumping of water uphill is

Irreversible process

Spontaneous process

Non spontaneous

None of these

21. Unit of heat is SI system is

Cal

KCaL

22. Evaporation of water is

An exothermic change

A process where no heat changes occur

An endothermic change

A process accompanied by chemical reaction

23. Free energy change for a reversible process is:

Equal to zero

Unpredictable

24. If internal energy of the system is increased

Temperature of the system may rise

All

Chemical reaction may take place

Change in state of the system is increased

25. The S.I unit of heat and energy is

Calorie

None of these

Joules

Watt

Page 2 of 5

26. Unit of heat in S.I system is

Kcal

Cal

27. Which law among the following has same net change whether it takes place directly or indirectly?

Hess’s law

Boyle’s law

Henry’s law

Graham’s law

28. If coefficients of a chemical equation are doubled, the enthalpy change will

Be double

Not change

None of these

Be half

29. System in which there is no exchange of matter, work or energy from surroundings is

Isolated

Closed

Isothermal

Adiabatic

30. What type of chemical reaction absorbs energy and requires energy for the reaction occur?

Synthesis

Endothermic

Exothermic

Both a and b

31. When a bond breaks

Temperature increases

Heat is absorbed

Heat is evolved

No change in heat contents takes place

32. Quantity of heat evolved or absorbed during reaction measure according to

∆E = q + w

∆H = ∆E + P∆V

Q = m x X x ∆ T

P∆V + nRT

33. In measurement of melting point of solid, the leaker used will be

Surrounding

State

System

Phase

34. Enthalpy of formation of HF and HCl are – 161 kJ and -92 kJ respectively. Which of the following statements is incorrect?

The affinity of fluorine to hydrogen is greater than the affinity of chlorine to hydrogen

HCl is more stable than HF

HF is more stable than HCl

HF and HCl are endothermic compounds

35. The reason of kinetic energy of the molecules of a gaseous substance among the following is

Rotational motion

Vibrational motion

The sum of all motions which are possible

Translational motion

36. The value of ∆Hо₋н is 109 kcal mol¯¹. Then formation of one mole of water in gaseous state form H(g) and O(g) is accompanied by

Absorption of 218 kcal of energy

Release of 109 kcal of energy

Unpredictable

Release of 218 kcal of energy

37. The unit which indicates the largest amount of energy is

Erg

Electron – volt

Joule

Calorie

38. What is the entropy change (in JK¯¹ mol¯¹) when one mole of ice is converted into water at 0°C? (The enthalpy change for the conversion of ice to liquid water is 6.0 kJ mol¯¹ at 0°C)

21.98

2.013

20.13

2.198

39. In general, for exothermic reactions to be spontaneous

Temperature has no effect

Temperature should be high

Temperature should be zero

Temperature should be low

40. What type of reaction releases energy and does not require initial energy to occur?

Both a and b

Decomposition

Exothermic

Endothermic

41. When enthalpy and entropy change for a chemical reaction are – 2.5 x 10³ cals and 7.4 cals deg¯¹ respectively. Predict that reaction at 298 K is

Reversible

Non-spontaneous

Irreversible

Spontaneous

42. The bond dissociation energies of H₂, CL₂ and HCl are 104, 58 and 103 kcal respectively. The enthalpy of formation of HCl gas will be

-88 kcal

-22 kcal

-11 kcal

-44 kcal

43. Change in enthalpy of a system can be calculated by following relationship

∆H = ∆E – PV

∆H = ∆E + Pv

∆H = ∆E – d

∆H = ∆E + d

44. If internal energy of a system is increased

Chemical reaction can take place

All

Change in state of system can occur

Temperature of the system may rise

45. The internal energy change when a system goes form state A to B is 40 kJ.mol. If the system goes from A to B by a reversible path and returns to state A by an irreversible path what would be the net change in internal energy?

Zero

> 40 kJ

40 kJ

< 40 kJ

46. One mole of an ideal gas expands isothermally to ten times its original volume. The change in entropy is

2.303 R

100.0 R

10.0 R

0.1 R

47. Two fundamental ways to transfer energy are

Heat and volume

Pressure and temperature

Pressure and volume

Heat and work

48. Enthalpy of combustion for food, fuel and other compounds can be measured accurately by

Bomb Calorimeter

Thermometer

Glass Calorimeter

Monometer

49. 10.16 g of graphite is burnt in a bomb calorimeter and the temperature rise recorded is 3.78 K. Calculate the enthalpy of combustion of graphite if the heat capacity is 86.02 KJ K¯¹

-27 KJ/mole

395 KJ/mole

190 KJ/mole

386 KJ/mole

50. Which of the following statement is contrary to first law of thermodynamics?

One form of energy can be transferred to an equivalent amount of the kind of energy

Continuous production of mechanical work without supplying an equivalent amount of heat energy

Work done is independent of its path

An equivalent amount of heat energy can neither be created nor destroyed

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51. The enthalpies of combustion of carbon and carbon monoxide are -390 kJ mol¯¹ and -278 kJ mol¯¹ respectively. The enthalpy of formation of carbon monoxide is

-668 kJ mol¯¹

-112 kJ mol¯¹

668 kJ mol¯¹

112 kJ mol¯¹

52. Mechanical work is especially important in systems that contain

Solid-liquid

Liquid-liquid

Solid-solid

Gases

53. In order to decompose 9 g of water 142.5 kJ of heat is required. Hence enthalpy of formation of water is

-285 kJ

+285 kJ

-142.5 kJ

+142.5 kJ

54. Endothermic changes are indicated through

Breaking of chemical bonds

All of these

Making of chemical bond

Burning of carbon

55. Which one is not state function?

Internal energy

Enthalpy

Work

Gibbs free energy

56. Which type of reactions cannot occur spontaneously?

Endothermic

Exothermic

Both a and b

Neither

57. The law of thermodynamics that provides the basis for the determination of absolute entropy of substance is

Second law

Zeroth law

Third law

First law

58. Sublimation, vaporization, melting and p photosynthesis all are examples of

Physical process

Endothermic process

Chemical process

Biochemical process

59. A spontaneous change means

A lowering of energy

A lowering of free energy

An increase in internal energy

No energy change

60. Reaction in which heat is evolved

Exothermic

Spontaneous

Endothermic

Non-spontaneous

61. Which statement describes characteristics of an endothermic reaction?

The sign of H is negative, and the products have more potential energy than the reactants

The sign of H is negative, and the products have less potential energy than the reactants

The sign of H is positive, and the products have less potential energy than the reactants

The sign of H is positive and the products a have more potential energy than the reactant

62. A mixture of ice and water contains 60 g of ice and water. If 60 J of heat energy is removed from this mixture, some of the

Ice will melt

Water will freeze

Water will vaporize

Ice will sublime

63. Standard enthalpy and standard entropy changes for the oxidation of ammonia at 298 K are -382.64kJ mol¯¹ and -145.6kJ¯¹ mol¯¹ respectively. Standard Gibbs energy change for the same reaction at 298 K is

-439.3 kJ mol¯¹

-339.3 kJ mol¯¹

-221.1 kJ mol¯¹

-523.3 kJ mol¯¹

64. ______ is the study about energy of a chemical system

Thermodynamics

Thermochemistry

Kinetics

Stoichiometry

65. A chemist heated a balloon by supplying 600 J of heat. The balloon expands doing 200 J of work against the atmospheric pressure. The change in internal energy of

-400J

0 J

= - k719

= + k319

66. What would be the heat released when an aqueous solution containing 0.5 mole of HNO₃ is mixed with 0.3 mol of OH¯ (enthalpy of neutralization is -57.1 kJ)

28.5 kJ

1.7 kJ

17.1kJ

45.7 kJ

67. Which one is not a state function?

Enthalpy

Gibbs free energy

Work

Internal energy

68. All the naturally occurring processes proceed spontaneously in a direction which lead to

Decrease of entropy

Decrease of free energy

Increase of free energy

Increase of enthalpy

69. The best characteristic of spontaneous reactions among the following is that

It is not irreversible

None of these

It is irreversible

It is reversible

70. The enthalpies of all elements in their standard states are

Negative

Positive

Zero

Unity

71. Enthalpy of a reaction can be measured by

Thermometer

Glass calorimeter

Barometer

Manometer

72. The amount of heat which is involved during the completion of a chemical reaction at 25°C and 1 atmospheric pressure is called

Hat of formation

Heat of combustion

Heat of neutralization

Enthalpy of reaction

73. Most of the reactions which give stable products are

Exothermic

Isothermal

None of these

Endothermic

74. The apparatus used to measure the enthalpy of combustion of a substance is

Copper calorimeter

Bomb calorimeter

Glass calorimeter

All above

75. Which of the following value of ∆Hf’ represent that the product is least stale?

+21.4 kcal mol¯¹

-231.6 kcal mol¯¹

+64.8 kcal mol¯¹

-94.0 kcal mol¯¹

Page 4 of 5

76. The energy required to break 1 mole of bonds to form neutral atom is

Bond length

Bond strength

None of these

Bond energy

77. The ∆H values for reaction C + ½ O₂ → CO and CO + ½ O₂ → CO₂ are 100 and 200 kJ respectively. The heat of reaction for C + O₂ → CO₂ will be

150 kJ

50 kJ

100 kJ

300 kJ

78. If an endothermic reaction is allowed to take place very rapidly in the air, the temperature of the surrounding air

Remains constant

Decreases

Remains same

Increases

79. Burning of coal in air is initiated by a spark and it is an example of spontaneous reaction because

Burning of coal is and endothermic process

None of these

Coal and air react giving a reversible reaction

Burning of coal in air releases large amount of energy

80. A cylinder of gas supplied by PSO is assumed to contain 14 kg of butane. If a normal family requires 20,000 kJ of energy per day for cooking, butane gas in the cylinder last for ……. Days (∆Hc of C₄H₁₀ = -2658 kJ per mole)

15 days

20 days

50 days

32 days

81. Form the above data, the standard heat of formation of KOH in kcal mol¯¹ is

68 – 48 + 14

68 + 48 + 14

– 68 + 48 – 14

– 68 – 48 + 14

82. If at 298 K the bond energies of C-H, C-C, C=C and H-H bonds are respectively 414, 347, 615 and 435 kJ mol¯¹, the value of enthalpy change for the reaction H₂C = CH₂(g) + H₂(g) → H₃C – CH₃(g) at 298 K will be

-250 kJ

+250 kJ

+125 kJ

-125 kJ

83. Which of the following unit represent the largest amount of energy?

Joule

Electron – volt

Erg

Calorie

84. Conversion of copper hydroxide into copper oxide and water is an example of

Combustion

Respiration

Neutralization

Thermal decomposition

85. Four containers hold the following quantity at the same temperature. Which one has the highest heat capacity?

1 kg H₂O

2 kg H₂O

3 kg H₂O

4 kg H₂O

86. Choose the S.I units for molar heat capacity among the following

Joule deg¯¹ Kg¯¹

Joule deg¯¹ atom¯¹

Joule deg¯¹ mol¯¹

Joule cm¯¹ deg¯¹

87. When enthalpy of reactants is higher than products, then reaction will be

Exothermic

Endothermic

Non-spontaneous

Spontaneous

88. An endothermic reaction is one in which

Heat is evolved

Heat is converted into mechanical work

Heat is converted into electricity

Heat is absorbed

89. For a melting of a solid at 25°C, the fusion process requires energy equivalent to 2906 Joules to be added to system considering the process to be reversible at fusion point, the entropy change of the process is

2.33 JK¯¹

Insufficient data

9.75 JK¯¹

11.272 JK¯¹

90. All of the following are state function except

91. The reaction is spontaneous if the cell potential is

Negative

Positive

Zero

Infinite

92. A particular reaction has a negative value for the energy change. Then at ordinary temperature

It has a large + ve value for enthalpy change

It has a + ve value for the entropy change and a – ve value for the enthalpy change

It has a large – ve value for the entropy change

It has small + ve value for enthalpy change

93. The molar heat capacity of water at constant pressure, Cᵨ, is 75 JK¯¹ mol¯¹. When 1.0 kJ of heat is supplied to 100 g of water which is free to expand, the increase in temperature of water is

4.8 K

1.2 K

2.4 K

6.6 K

94. Most of the thermodynamic parameters are

System

Surrounding

Phase

State function

95. An exothermic reaction is one in which the reacting substances

Have the same energy as the products

Have less energy than the products

Are at a higher temperature than the products

Have more energy than the products

96. Which of the following is not correct?

The absolute value of enthalpy (H) can be determined experimentally

The heat of reaction at constant volume is denoted by ∆E.

Neutralization is always exothermic

Dissolution on NH₄Cl in excess of water is an endothermic process

97. 1 mole of H₂SO₄ is mixed with 2 mole of NaOH. The heat evolved will be

2 x 57.3 kJ

57.3 kJ

Cannot be predicted

57.3/2 kJ

98. Heat exchanged in a chemical reaction at constant temperature and pressure is called

Entropy change

Internal energy change

Free energy change

Enthalpy change

99. The heat required to raise the temperature of a body by 1 K is called

None of these

Water equivalent

Thermal capacity

Specific heat

100. For the reaction NaOH + HCl → NaCl + H₂O the change in enthalpy is called

Heat of combustion

Heat of reaction

Heat of sublimation

Heat of neutralization

Page 5 of 5

101. Total energy depends upon the state of system

Enthalpy

All above

Free energy of reaction

Entropy of reaction

102. Hess’s law deals with

Equilibrium constant

Rate of reaction

Changes in heat or reaction

Influence of pressure on volume of a gas

103. When 50 cm³ of 0.2 n H₂SO₄ is mixed with 50 cm³ of 1 N KOH, the heat liberated is

57.3 kJ

573 kJ

11.46 kJ

573 J

104. Two fundamental ways to transfer energy are

Heat and work

Pressure and temperature

Pressure and volume

Heat and volume

105. C (diamond) → C(Graphite), ∆ H = -ve. This show that

Graphite has more energy than diamond

Graphite is more stable than diamond

Stability cannot to predicated

Both are equally stable

106. When enthalpy of reactants is higher than product then reaction will be

Spontaneous

Non-spontaneous

Endothermic

Exothermic

107. Total energy of a system is

P.E, + K.E.

P.E. + heat energy

P.E, + mechanical energy

K.E, + heat energy

108. When water is added to quick lime, the reaction is

Exothermic

Endothermic

Explosive

Photochemical

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Mustansar KhanLast Updated: October 14, 2025

Important Thermo Chemistry Question and Answer

Thermo Chemistry Practice Test Online With Explanation

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