JEE Chemistry Thermodynamics MCQs Set A

Question: Thermodynamics is not concerned about____.

• a) the rate at which a reaction proceeds
• b) the feasibility of a chemical reaction
• c) the extent to which a chemical reaction proceeds
• d) energy changes involved in a chemical reaction

Answer: the rate at which a reaction proceeds

Question: Which of the following statements is not true regarding the laws of thermodynamics ?

• a) It deal with energy changes of microscopic systems
• b) It deal with energy changes of macroscopic systems
• c) It does not depends on the rate at which these energy transformations are carried out
• d) It depends on initial and final states of a system undergoing the change.

Answer: It deal with energy changes of microscopic systems

Question: A ___________ in thermodynamics refers to that part of universe in which observations are made and remaining universe constitutes the……………...

• a) system, surroundings
• b) system, boundary
• c) surroundings, system
• d) system, surroundings

Answer: system, surroundings

Question: The universe refers to

• a) both system and surroundings
• b) only surroundings
• c) only system
• d) None of these

Answer: both system and surroundings

Question: Which of the following statements is correct?

• a) The presence of reactants in a closed vessel made up of copper is an example of a closed system
• b) The presence of reactants in a thermos flask or any other closed insulated vessel is an example of a closed system.
• c) There is an exchange of energy as well as matter between the system and the surroundings in a closed system.
• d) The presence of reacting species in a covered beaker is an example of open system

Answer: The presence of reactants in a closed vessel made up of copper is an example of a closed system

Question: Which of the following is closed system ?

• a) Rocket engine during propulsion
• b) Pressure cooker
• c) Tea placed in a steel kettle
• d) Jet engine

Answer: Rocket engine during propulsion

Question: An isolated system is that system in which

• a) There is exchange of mass and energy with the surroundings
• b) There is no exchange of energy with the surroundings
• c) There is no exchange of mass or energy with the surroundings
• d) There is exchange of mass with the surroundings

Answer: There is exchange of mass and energy with the surroundings

Question: The state of a thermodynamic system is described by its measurable or macroscopic (bulk) properties. These are

• a) Pressure and temperature
• b) Volume, temperature and amount
• c) Pressure, volume, temperature and amount
• d) Pressure and volume

Answer: Pressure and temperature

Question: Which of the following are not state functions ?

(I) q + w     (II) q
(III) w        (IV) H - TS

• a) (I), (II) and (III)
• b) (II) and (III)
• c) (II), (III) and (IV)
• d) (I) and (IV)

Answer: (I), (II) and (III)

Question: Among the following the state function(s) is (are)

(i) Internal energy
(ii) Irreversible expansion work
(iii) Reversible expansion work
(iv) Molar enthalpy

• a) (i) and (iv)
• b) (ii) and (iii)
• c) (i), (ii) and (iii)
• d) (i) only

Answer:  (i) and (iv)

Question:

• a) Both on initial and final state
• b) None of these
• c) Final state
• d) Initial state

Answer: Both on initial and final state

Question: ______ is a quantity which represents the total energy of the system

• a) Internal energy
• b) Electrical energy
• c) Chemical energy
• d) Mechanical energy

Answer: Internal energy

Question: Which of the following factors affect the internal energy of the system ?

• a) All of the above
• b) Matter enters or leaves the system.
• c) Work is done on or by the system
• d) Heat passes into or out of the system.

Answer: All of the above

Question:  The system that would not allow exchange of heat between the system and surroundings through its boundary is considered as

• a) adiabatic
• b) isochoric
• c) isothermal
• d) isobaric

Answer: adiabatic

Question: The enthalpy change of a reaction does not depend on

• a) Different intermediate reactions
• b) Nature of reactants and products
• c) The state of reactants and products
• d) Initial and final enthalpy change of a reaction

Answer: Different intermediate reactions

Question: The q is ________  when heat is transferred from the surroundings to the system and q is………………………..

• a) positive , negative
• b) high, low
• c) negative , positive
• d) low, high

Answer: positive , negative

Question: Adiabatic expansions of an ideal gas is accompanied by

• a)

  

• b) increase in temperature
• c) no change in any one of the above properties
• d) All of these

Answer:

Question: Which of the following statements is incorrect?

• a) Both
• b) q is a path dependent function
• c) H is a state function
• d) None of these

Answer: Both

Question: Figure below is showing that one mole of an ideal gas is fitted with a frictionless piston. Total volume of the gas is V_i and pressure of the gas inside is p. If external pressure is p_ex which is greater than p is applied, piston is moved inward till the pressure inside becomes equal to p_ex.

• a) Work done
• b) Volume change
• c) Pressure change
• d) Temperature change

Answer: Work done

Question: When 1 mol of a gas is heated at constant volume, temperature is raised from 298 to 308 K. If heat supplied to the gas is 500 J, then which statement is correct ?

• a)

  

• b)

  

• c)

  

• d) None of these

Answer:

Question: The work done during the expansion of a gas from a volume of 4 dm³ to 6 dm³ against a constant external pressure of 3 atm is (1 L atm = 101.32 J)

• a) – 608 J
• b) – 304 J
• c) – 6 J
• d) + 304 J

Answer: – 608 J

Question: Which of the following statements/relationships is not correct in thermodynamic changes ?

• a)

  

• b)

  

• c)

  

• d) All of these

Answer:

Question: An ideal gas expands in volume from 1×10^–3 to 1 × 10^–2 m³ at 300 K against a constant pressure of 1×105 Nm^–2. The work done is

• a) – 900 J
• b) 270 kJ
• c) – 900 kJ
• d) 900 kJ

Answer: – 900 J

Question:

• a) only gases
• b) only liquids
• c) only solids
• d) both solids and liquids

Answer: only gases

Question: If a reaction involves only solids and liquids which of the following is true ?

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: During isothermal expansion of an ideal gas, its

• a) enthalpy remains unaffected
• b) enthalpy reduces to zero
• c) enthalpy decreases
• d) internal energy increases

Answer: enthalpy remains unaffected

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: For a reaction in which all reactants and products are liquids, which one of the following equations is most applicable ?

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:  The relationship between enthalpy change and internal energy change is

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:

• a) – 3 RT
• b) – RT
• c) + RT
• d) + 3 RT

Answer: – 3 RT

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:  Among the following, the intensive properties are

(i) molar conductivity (ii) electromotive force
(iii) resistance            (iv) heat capacity

• a) (ii) and (iii)
• b) (i) and (iv)
• c) (i), (ii) and (iii)
• d) (i) only

Answer: (ii) and (iii)

Question: Which is an extensive property of the system ?

• a) Volume
• b) Temperature
• c) Viscosity
• d) Refractive index

Answer: Volume

Question: Which of the following is an example of extensive property?

• a) Mass
• b) Temperature
• c) Density
• d) Pressure

Answer: Mass

Question: Which of the following factors do not affect heat capacity?

• a) Temperature of the system
• b) Composition of system
• c) Size of system
• d) Nature of system

Answer: Temperature of the system

Question: The heat required to raise the temperature of body by 1 C° is called

• a) thermal capacity
• b) None of these
• c) specific heat
• d) water equivalent

Answer: thermal capacity

Question: Equal volumes of two monoatomic gases, A and B, at same temperature and pressure are mixed. The ratio of specific heats (C_p/C_v) of the mixture will be

• a) 1.67
• b) 1.50
• c) 0.83
• d) 3.3

Answer: 1.67

Question: The molar heat capacity of water at constant pressure is 75 JK^–1 mol^–1. When 1kJ of heat is supplied to 100 g of water, which is free to expand, the increase in temperature of water is

• a) 2.4 K
• b) 6.6 K
• c) 1.2 K
• d) 4.8 K

Answer: 2.4 K

Question: Calorie is equivalent to

• a) 4.184 Joule
• b) 418.4 Joule
• c) 0.4184 Joule
• d) 41.84 Joule

Answer: 4.184 Joule

Question: Which of the following is not true regarding thermo-chemical equations?

• a) The coefficients in a balanced thermo-chemical equation refer to the number of molecules of reactants and products involved in the reaction
• b) The coefficients in a balanced thermo-chemical equation refer to the number of moles of reactants and products involved in the reaction
• c) Both
• d) None of these

Answer: The coefficients in a balanced thermo-chemical equation refer to the number of molecules of reactants and products involved in the reaction

Question: The enthalpies of elements in their standard states are taken as zero. The enthalpy of formation of a compound

• a) may be positive or negative
• b) is always positive
• c) is always negative
• d) is never negative

Answer: may be positive or negative

Question:

• a) – 1412 kJ/mol
• b) + 1412 kJ/mol
• c) – 141.2 kJ/mol
• d) + 14.2 kJ/mol

Answer: – 1412 kJ/mol

Question: The enthalpy change for a reaction does not depend upon

• a) the nature of intermediate reaction steps
• b) use of different reactants for the same product
• c) the differences in initial or final temperatures of involved substances
• d) the physical states of reactants and products

Answer: the nature of intermediate reaction steps

Question: On the basis of thermochemical equations (i), (ii) and (iii), find out which of the algebric relationships given in options (a) to (d) is correct

• a) x = y + z
• b) z = x + y
• c) x = y – z
• d) y = 2z – x

Answer: x = y + z

Question:

• a) 425 kJ mol^–1
• b) 290 kJ mol^–1
• c) 380 kJ mol^–1
• d) 245 kJ mol^–1

Answer: 425 kJ mol^–1

Question: Bond dissociation enthalpy of H₂, Cl₂ and HCl are 434 , 242 and 431 kJ mol^–1 respectively. Enthalpy of formation of HCl is:

• a) – 93 kJmol^–1
• b) 93 kJ mol^–1
• c) – 245 kJmol^–1
• d) 245 kJmol^–1

Answer: – 93 kJmol^–1

Question:

• a) –120.0 kJ mol^–1
• b) 1523.6 kJ mol^–1
• c) – 243.6 kJ mol^–1
• d) 553.0 kJ mol^–1

Answer: –120.0 kJ mol^–1

Question:

• a) + 6.2 kJ
• b) – 43.3 kJ
• c) + 10.3 kJ
• d) – 10.3 kJ

Answer: + 6.2 kJ

Question:

• a) – 175 kJ/mol
• b) 325 kJ/mol
• c) 525 kJ/mol
• d) – 325 kJ/mol

Answer: – 175 kJ/mol

Question:

• a) 41.2
• b) – 41.2
• c) 524.1
• d) – 262.5

Answer: 41.2

Question:

• a) – 1412 kJ/mol
• b) + 1412 kJ/mol
• c) – 141.2 kJ/mol
• d) + 14.2 kJ/mol

Answer: – 1412 kJ/mol

Question: Hess’s law is used to calculate

• a) enthalpy of reaction
• b) work done in reaction
• c) entropy of reaction
• d) All of the above

Answer: enthalpy of reaction

Question:

• a) Hess’s law of constant heat summation
• b) Standard enthalpy of a solution
• c) Born – Haber cycle of lattice enthalpy
• d) Standard enthalpy of a reaction

Answer: Hess’s law of constant heat summation

Question: The enthalpy change on breaking one mole of bonds completely to obtain atoms in the gas phase is known as

• a) enthalpy of atomization.
• b) enthalpy of formation
• c) enthalpy of sublimation
• d) enthalpy of vaporization

Answer: enthalpy of atomization.

Question:

• a) The enthalpy of atomization is same as the enthalpy of sublimation
• b) The enthalpy of atomization is same as the enthalpy of vaporisation
• c) The enthalpy of atomization is same as the bond enthalpy
• d) The enthalpy of atomization is same as the enthalpy of solution

Answer: The enthalpy of atomization is same as the enthalpy of sublimation

Question: The heat of combustion of a substance is

• a) Always negative
• b) Numerically equal to the heat of formation
• c) Unpredictable
• d) Always positive

Answer: Always negative

Question: During complete combustion of one mole of butane, 2658 kJ of heat is released. The thermochemical reaction for above change is

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: Given that heat of neutralisation of strong acid and strong base is – 57.1 kJ. The heat produced when 0.25 mole of HCl is neutralised with 0.25 mole of NaOH in aqueous solution is :

• a) 14.275 kJ
• b) 22.5 kJ
• c) 57.1 kJ
• d) 28.6 kJ

Answer: 14.275 kJ

Question:

• a) positive, endothermic
• b) negative,endothermic
• c) negative, exothermic
• d) positive ,exothermic

Answer: positive, endothermic

Question: Pick out the wrong statement

• a) A process that leads to increase in free energy will be spontaneous
• b) The entropy of a perfectly crystalline substance at absolute zero is zero
• c) A process accompanied by decrease in entropy is spontaneous under certain conditions
• d) The standard free energy of formation of all elements is zero

Answer: A process that leads to increase in free energy will be spontaneous

Question:

• a)

  

• b)

  

• c) Both
• d) None of these

Answer:

Question: Identify the correct statement regarding a spontaneous process:

• a) For a spontaneous process in an isolated system, the change in entropy is positive.
• b) Lowering of energy in the process is the only criterion for spontaneity
• c) Endothermic processes are never spontaneous
• d) Exothermic processes are always spontaneous

Answer: For a spontaneous process in an isolated system, the change in entropy is positive.

Question: A chemical reaction will be spontaneous if it is accompanied by a decrease of

• a) free energy of the system
• b) internal energy of the system
• c) enthalpy of the system
• d) entropy of the system

Answer: free energy of the system

Question: In which of the following entropy decreases?

• a) Crystallization of sucrose solution
• b) Rusting of iron
• c) Melting of ice
• d) Vaporization of camphor

Answer: Crystallization of sucrose solution