NEET Chemistry Thermodynamics MCQs Set B

Question: In thermodynamics a process is called reversible when

• a) System and surrounding change into each other
• b) There is no boundary between system and surrounding
• c) The surroundings are always in equilibrium with the system
• d) The system changes into the surroundings spontaneously

Answer: The surroundings are always in equilibrium with the system

Question:  The molar heat capacity of water at constant pressur e P is 75 J K^–1 mol^–1. When 1.0 kJ of heat is supplied to 1000 g of water, which is free to expand, the increase in temperature of water is

• a) 1.2 K
• b) 2.4 K
• c) 4.8 K
• d) 0.24 K

Answer: 0.24 K

Question: 16 kg oxygen gas expands at STP (1 atm) isobarically to occupy double of its original volume. The work done during the process is nearly

• a) 260 kcal
• b) 180 kcal
• c) 130 kcal
• d) 271 kcal

Answer: 271 kcal

Question:  The enthalpy and entropy change for a chemical reaction are –2.5 × 10³ cal and 7.4 cal K^–1 respectively. Predict the nature of reaction at 298 K is

• a) Spontaneous
• b) Reversible
• c) Irreversible
• d) Non-spontaneous

Answer: Spontaneous

Question:  The temperature at which the given reaction is at equilibrium

• a) 462.12 K
• b) 362.12 K
• c) 262.12 K
• d) 562.12 K

Answer: 462.12 K

Question:  One mole of a non ideal gas undergoes a change of state (2.0 atm, 3.0 L, 95 K) → (4.0 atm, 5.0 L, 245 K) with a change in internal energy ΔU = 30.0 L atm. The change in enthalpy of the process in L atm is

• a) 40.0
• b) 42.3
• c) 44.0
• d) 56.0

Answer: 44.0

Question: In an insulated container water is stirred with a rod to increase the temperature. Which of the following is true?

• a) ΔU = W ≠0, q = 0
• b) ΔU = W = q ≠ 0
• c) ΔU = 0, W = q ≠ 0 
• d) W = 0, ΔU = q ≠0

Answer:  ΔU = W ≠0, q = 0

Question:  Two atoms of hydrogen combine to form a molecule of hydrogen gas the energy of the H₂ molecule is

• a) Greater than that of separate atoms
• b) Equal to that of separate atoms
• c) Lower than that of separate atoms
• d) Sometimes lower and sometimes higher

Answer: Lower than that of separate atoms

Question:  The temperature of 15 ml of a strong acid increases by 2°C when 15 ml of a strong base is added to it. If 5 ml of each are mixed, temperature should increase by

• a) 0.6°C
• b) 0.3°C 
• c) 2°C
• d) 6°C

Answer:  2°C

Question:  The standard heat of formation of NO₂(g) and N₂O₄(g) are 8.0 and 4.0 kcal mol^–1 respectively. The heat of dimerisation of NO₂ in kcal is

• a) –12 kcal
• b) 12 kcal
• c) 4 kcal
• d) 16 kcal

Answer: –12 kcal

Question:   If   Then heat change during reaction of metal X with one mole of O₂ to form oxide to maximum extent is

• a) 360 kJ
• b) –360 kJ
• c) –180 kJ
• d) +180 kJ

Answer: –360 kJ

Question:  For a gaseous reaction :

ΔE is 17 kcal at 27°C. Assuming R = 2 cal K^–1 mol^–1 the value of ΔH for the above reaction will be

• a) 15.8 kcal
• b) 16.4 kcal
• c) 18.2 kcal
• d) 20.0 kcal

Answer: 18.2 kcal

Question:  A mixture of 2 mole of CO and 1 mol of O₂ is ignited. Correct relationship is

• a) ΔH = ΔU
• b) ΔH > ΔU
• c) ΔH < ΔU
• d) The relationship depends upon the capacity of vessel

Answer:  ΔH < ΔU

Question:   Bond dissociation energy of XY, X₂ and Y₂(all diatomic molecules) are in the ratio of 1 : 1 : 0.5 and ΔH_f of XY is –200 kJ mol^–1. The bond dissociation energy of X₂ will be

• a) 800 kJ mol^–1
• b) 200 kJ mol^–1
• c) 300 kJ mol^–1 
• d) 400 kJ mol^–1

Answer:  800 kJ mol^–1

Question: Vapour density of a gas is 8. Its molecular mass will be

• a) 8
• b) 16
• c) 32
• d) 64

Answer: 16

More Questions...........................................

Question:  If x mole of ideal gas at 27°C expands isothermally and reversibly from a volume of y to 10y, then the work done is

• a) w = x R 300 ln y
• b)

  

• c) w = – 300x R ln 10
• d)

  

Answer: w = – 300x R ln 10

Question:  Enthalpy of formation of NH₃ is – X kJ and ΔH_H–H, ΔH_N–H are respectively Y kJ mol^–1 and ΔZ kJ mol^–1. The value of ΔH_{N ≡ N} is

• a)

  

• b) – 3Y + 6Z – 2X
• c) 3Y + 6Z + X
• d) Y + 6X + Z

Answer: – 3Y + 6Z – 2X

Question:  A system X undergoes following changes

The overall process may be called as

• a) Reversible process
• b) Cyclic process
• c) Cyclic reversible process
• d) Isochoric process

Answer: Cyclic process

Question: The heat of neutralisation for strong acid and strong base forming 2 moles of water is

• a) – 2 × 57.1 kJ
• b) – 57.1 kJ
• c)

  

• d) Strong acid and strong base will not undergo neutralisation

Answer: – 2 × 57.1 kJ

Question:   The value of ΔH° in kJ for the reaction will be

• a) x + 4y – z – 2r
• b) r + z + 4y – x
• c) 2r + z + 4y + x
• d) x + 4y + z – 2r

Answer: x + 4y + z – 2r

Question:  The heat liberated on complete combustion of 1 mole of CH₄ gas to CO₂ (g) and H₂O(l) is 890 kJ. Calculate the heat evolved by 2.4 L of CH₄ on complete combustion.

• a) 95.3 kJ
• b) 8900 kJ
• c) 890 kJ
• d) 8.9 kJ

Answer: 95.3 kJ

Question:  The work done in an open vessel at 300 K, when 112 g iron reacts with dil HCl to give FeCl₂ , is nearly

• a) 1.1 kcal
• b) 0.6 kcal
• c) 0.3 kcal
• d) 0.2 kcal

Answer: 1.1 kcal

Question: Which statement is correct?

• a)

  

• b)

  

• c)

  

• d) All of these

Answer:

Question:  A schematic representation of enthalpy changes for the reaction, is given below.

The missing value is

• a) + 10.5 kJ
• b) – 11.05 kJ
• c) – 110.5 kJ
• d) – 10.5 J

Answer: – 110.5 kJ

Question:  Which of the following equations represent standard heat of formation of CH₄?

• a) C_(diamond)+ 2H₂(g) → CH₄(g) 
• b) C_(graphite)+ 2H₂(g) → CH₄(g)
• c) C_(diamond)+ 4H(g) → CH₄(g)
• d) C_(graphite)+ 4H(g) → CH₄(g)

Answer:  C_(graphite)+ 2H₂(g) → CH₄(g)

Question:   Different types of systems are given below

The A and B systems respectively are

• a) Open system, Closed system
• b) Isolated system, Closed system
• c) Adiabatic system, Isolated system
• d) Closed system, Isolated system

Answer: Closed system, Isolated system

Question: Set of intensive properties is shown by

• a) Mole fraction, standard electrode potential, heat capacity
• b) Viscosity, refractive index, specific heat
• c) Density, Gibbs free energy, internal energy
• d) Number of moles, molarity, electrode potential

Answer: Viscosity, refractive index, specific heat

Question: For the expansion occurring from initial to final stage in finite time, which is incorrect?

• a) Equilibrium exist in initial and final stage
• b) Work obtained is maximum
• c) Driving force is much greater than the opposing force
• d) Both (1) & (2)

Answer: Work obtained is maximum

Question:  The enthalpy of fusion of water is 1.435 kcal/mol. The molar entropy change for the melting of ice at 0°C is 

• a) 5.260 cal/(mol K)
• b) 0.526 cal/(mol K)
• c) 10.52 cal/(mol K)
• d) 21.04 cal/(mol K)

Answer: 5.260 cal/(mol K)

Question: Three moles of an ideal gas expanded spontaneously into vacuum. The work done will be

• a) Infinite
• b) 3 Joules
• c) 9 Joules
• d) Zero

Answer: Zero

Question: Which of the following are not state functions ? (I) q + w (II) q (III) w (IV) H-TS

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

Answer: (II) and (III)

Question:  Given that bond energies of H–H and Cl – Cl are 430 kJ/mol and 240 kJ/mol respectively and Δ_fH of HCl is –90kJ/mol. Bond enthalpy of HCl is 

• a) 245 kJ mol^–1
• b) 2909 kJ mol^–1
• c) 380 kJ mol^–1
• d) 425 kJ mol^–1

Answer:  425 kJ mol^–1

Question: Which of the following pairs of a chemical reaction is certain to result in a spontaneous reaction ?

• a) Exothermic and decreasing disorder
• b) Endothermic and increasing disorder
• c) Exothermic and increasing disorder
• d) Endothermic and decreasing disorder

Answer: Exothermic and increasing disorder

Question: Identify the correct statement regarding entropy

• a) At absolute zero of temperature, the entropy of all crystalline substances is taken to be zero
• b) At absolute zero of temperature, the entropy of a perfectly crystalline substance is +ve
• c) At absolute zero of temperature, entropy of a perfectly crystalline substance is taken to be zero
• d) At 0°C, the entropy of a perfectly crystalline substance is taken to be zero

Answer: At absolute zero of temperature, entropy of a perfectly crystalline substance is taken to be zero

Question:  One mole of an ideal gas at 300 K is expanded isothermally from an initial volume of 1 litre to 10 litres. The ΔE for this process is (R = 2 cal. Mol^–1K^–1)

• a) 1381.1 cal
• b) Zero
• c) 163.7 cal
• d) 9 L atm

Answer: Zero

Question:   At 27°C latent heat of fusion of a compound is 2930 J/mol. Entropy change is

• a) 9.77 J/mol·K
• b) 10.77 J/mol·K
• c) 9.07 J/mol·K
• d) 0.977 J/mol·K

Answer: 9.77 J/mol·K

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

• a) q = ΔU = –500 J, w = 0 
• b) q = ΔU = 500 J, w = 0
• c) q = w = 500 J, ΔU = 0 
• d) ΔU = 0, q = w = –500 J

Answer:  q = ΔU = 500 J, w = 0

Question:  Enthalpy of is negative. If enthalpy of combustion of CH₄ and CH₃OH are x and y respectively. Then which relation is correct?

• a) x > y 
• b) x < y 
• c) x = y 
• d) x ≥ y

Answer:  x > y 

Question: Unit of entropy is

• a) JK^–1 mol^–1
• b) J mol^–1
• c) J^–1 K^–1 mol^–1
• d) JK mol^–1

Answer:  JK^–1 mol^–1

Question: In a closed insulated container a liquid is stirred with a paddle to increase the temperature which of the following is true?

• a) ΔE = W ≠ 0, q = 0
• b) ΔE = W = q ≠ 0
• c) ΔE = 0, W = q ≠0 
• d) W = 0, ΔE = q ≠0

Answer:  ΔE = W ≠ 0, q = 0

Question:  2 mole of ideal gas at 27°C temperature is expanded reversibly from 2 lit. to 20 lit. Find entropy change (R =2 cal/mol K)

• a) 92.1
• b) 0
• c) 4
• d) 9.2

Answer: 9.2

Question:   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)

• a) 20.13
• b) 2.013
• c) 2.198
• d) 21.98

Answer: 21.98

Question:    The molar heat capacity of water at constant pressure, C, is 75 J K^–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

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

Answer: 2.4 K

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

Answer: –608 J

Question: Three moles of an ideal gas expanded spontaneously into vacuum. The work done will be

• a) Infinite
• b) 3 Joules
• c) 9 Joules
• d) Zero

Answer: Zero

Question:  The enthalpy of fusion of water is 1.435 kcal/mol. The molar entropy change for the melting of ice at 0°C is

• a) 5.260 cal/(mol K)
• b) 0.526 cal/(mol K)
• c) 10.52 cal/(mol K)
• d) 21.04 cal/(mol K)

Answer: 5.260 cal/(mol K)

Question:  The enthalpy of hydrogenation of cyclohexene is –119.5 kJ mol^–1. If resonance energy of benzene is –150.4 kJ mol^–1, its enthalpy of hydrogenation would be

• a) –358.5 kJ mol^–1
• b) –508.9 kJ mol^–1
• c) –208.1 kJ mol^–1 
• d) –269.9 kJ mol^–1

Answer:  –208.1 kJ mol^–1 

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

Answer: –608 J

Question:   The molar heat capacity of water at constant pressure, C, is 75 J K–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

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

Answer: 2.4 K

Question:   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)

• a) 20.13
• b) 2.013
• c) 2.198
• d) 21.98

Answer: 21.98

Question:  Heat of combustion for C(s), H₂(g) and CH₄(g)  are –94, –68 and –213 kcal/mol, then ΔH forC(s) + 2H₂(g) → CH₄(g) is

• a) –17 kcal
• b) –111 kcal
• c) –170 kcal
• d) –85 kcal

Answer: –17 kcal

Question:  2 mole of ideal gas at 27°C temperature is expanded reversibly from 2 lit. to 20 lit. Find entropy change (R =2 cal/mol K)

• a) 92.1
• b) 0
• c) 4
• d) 9.2

Answer: 9.2

Question:   For the reaction

,which one is true?

• a) ΔH = ΔE – RT
• b) ΔH = ΔE + RT 
• c) ΔH = ΔE + 2RT
• d) ΔH = ΔE – 2RT

Answer:  ΔH = ΔE – RT

Question:  In the reaction : S + 3/2 O₂→ SO₃+ 2x kcal and SO₂+ 1/2 O₂→SO₃+ y kcal, the heat of formation of SO₂ is

• a) (2x + y)
• b) (x – y)
• c) (x + y)
• d) (y – 2x)

Answer: (y – 2x)

Question:

What is heat of formation of CO?

• a)

  

• b) 2x – y
• c) y – 2x
• d)

  

Answer:

Question: For a reaction to occur spontaneously

• a) ΔH must be negative
• b) ΔS must be negative 
• c) (ΔH – TΔS) must be negative 
• d) (ΔH + TΔS) must be negative

Answer:  (ΔH – TΔS) must be negative 

Question:  Which reaction, with the following values of ΔH, ΔS, at 400 K is spontaneous and endothermic?

• a) ΔH = –48 kJ; ΔS = + 135 J/K 
• b) ΔH = –48 kJ; ΔS = – 135 J/K
• c) ΔH = +48 kJ; ΔS = + 135 J/K 
• d) ΔH = +48 kJ; ΔS = – 135 J/K

Answer:  ΔH = +48 kJ; ΔS = + 135 J/K 

Question: Which of the following pairs of a chemical reaction is certain to result in a spontaneous reaction ?

• a) Exothermic and decreasing disorder
• b) Endothermic and increasing disorder
• c) Exothermic and increasing disorder
• d) Endothermic and decreasing disorder

Answer: Exothermic and increasing disorder

Question: Three moles of an ideal gas expanded spontaneously into vacuum. The work done will be

• a) Infinite
• b) 3 Joules
• c) 9 Joules
• d) Zero

Answer: Zero

Question:  For the gas phase reaction,

which of the following conditions is correct ? 

• a) ΔH > 0 and ΔS < 0 
• b) ΔH = 0 and ΔS < 0
• c) ΔH > 0 and ΔS > 0
• d) ΔH < 0 and ΔS < 0

Answer:  ΔH > 0 and ΔS > 0