31 Year NEET Previous Year Questions: Thermodynamics - 1

Question 1

What is the entropy change (in JK^–1 mol^–1) when one mole of ice is converted into water at 0º C? (The enthalpy change for the conversion of ice to liquid water is 6.0 kJ mol^–1 at 0ºC) [2003]

Accepted Answer

21.98

Answer

20.13

Answer

2.013

Answer

2.198

Question 2

The densities of graphite and diamond at 298 K are 2.25 and 3.31g cm^–3, respectively. If the standard free energy difference (ΔGº) is equal to 1895 J mol^–1, the pressure at which graphite will be transformed into diamond at 298 K is: [2003]

Accepted Answer

9.92 × 10⁸ Pa

Answer

9.92 × 10⁵ Pa

Answer

9.92 × 10⁷ Pa

Answer

9.92 × 10⁶ Pa

Question 3

For which one of the following equations is ΔHº_react equal to ΔH_fº for the product? [2003]

Accepted Answer

Answer

Answer

Answer

Question 4

For the reaction C₃H_8(g) + 5O_2(g)→ 3CO_2(g) + 4H₂O_(l)at constant temperature, ΔH – ΔE is: [2003]

Accepted Answer

&ndash; 3 RT

Answer

&ndash; RT

Answer

+ RT

Answer

+ 3 RT

Question 5

If the bond energies of H-H, Br-Br, and HBr are 433, 192 and 364 kJ mol^–1respectively, the ΔH° for the reaction H₂(g) + Br₂(g) → 2HBr(g) is: [2004]

Accepted Answer

&ndash; 103 kJ

Answer

&ndash; 261 kJ

Answer

+ 103 kJ

Answer

+ 261kJ

Question 6

The standard enthalpy and standard entropy changes for the oxidation of ammonia at 298 K are -382.64 kJ mol^–1 and -145.6 JK^–1 mol^–1, respectively.
Standard Gibb's energy change for the same reaction at 298 K is: [2004]

Accepted Answer

- 339.3 kJ mol^–1

Answer

-22.1 kJ mol^–1

Answer

- 439.3 kJ mol^–1

Answer

- 523.2 kJ mol^–1

Question 7

Considering entropy(S) as a thermodynamic parameter, the criterion for the spontaneity of any process is: [2004]

Accepted Answer

ΔS_system + ΔS_surroundings > 0

Answer

ΔS_system - ΔS_surroundings > 0

Answer

ΔS_system > 0 only

Answer

ΔS_surroundings > 0 only

Question 8

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: (1L atm = 101.32 J) [2004]

Accepted Answer

&ndash; 608J

Answer

&ndash; 6J

Answer

+ 304J

Answer

&ndash; 304J

Question 9

The absolute enthalpy of neutralisation of the reaction: MgO (s) + 2HCl (aq) —→ MgCl₂(aq) + H₂O (l) will be:[2005]

Accepted Answer

Less than -57.33 kJ mol^-1

Answer

-57.33 kJ mol^-1

Answer

Greater than -57.33 kJ mol^-1

Answer

57.33 kJ mol^-1

Question 10

A reaction occurs spontaneously if: [2005]

Accepted Answer

TΔS > ΔH and both ΔH and ΔS are + ve

Answer

TΔS < ΔH and both ΔH and ΔS are + ve

Answer

TΔS > ΔH an d ΔH is + ve and ΔS is -ve

Answer

TΔS = ΔH and both ΔH and ΔS are + ve

Question 11

Which of the following pairs of a chemical reaction is certain to result in a spontaneous reaction? [2005]

Accepted Answer

Exothermic and increasing disorder

Answer

Exothermic and decreasing disorder

Answer

Endothermic and increasing disorder

Answer

Endothermic and decreasing disorder

Question 12

The enthalpy of hydrogenation of cyclohexene is –119.5 kJ mol^–1. If the resonance energy of benzene is –150.4 kJ mol^–1, its enthalpy of hydrogenation would be: [2006]

Accepted Answer

– 208.1 kg mol^–1

Answer

– 269.9 kg mol^–1

Answer

– 358.5 kg mol^–1

Answer

– 508.9 kg mol^–1

Question 13

The enthalpy and entropy change for the reaction Br₂(l) + Cl₂(g) → 2BrCl(g) are 30kJ mol^–1 and 105 JK^–1 mol^–1respectively.The temperature at which the reaction will be in equilibrium is: [2006]

Accepted Answer

285.7 K

Answer

273 K

Answer

450 K

Answer

300 K

Question 14

Identify the correct statement for change of Gibbs energy for a system (ΔG_system) at constant temperature and pressure: [2006]

Accepted Answer

If ΔG_system= 0, the system has attained equilibrium.

Answer

If ΔG_system = 0, the system is still moving in a particular direction.

Answer

If ΔG_system< 0 , the process is not spontaneous.

Answer

None of These

Question 15

Assume each reaction is carried out in an open container. For which reaction will ΔH = ΔE? [2006]

Accepted Answer

H₂ (g) + Br₂ (g) → 2 HBr (g)

Answer

C(s) + 2H₂O (g) → 2H₂ (g) + CO₂ (g)

Answer

PCl₅ (g) → PCl₃ (g) + Cl₂ (g)

Answer

2CO (g) + O₂ (g) → 2CO₂ (g)

Question 16

Consider the following reactions: [2007]

(i)

(ii)

(iii)

(iv)

Enthalpy of formation of H₂O (l) is

Accepted Answer

– X₂ kJ mol^{– 1}

Answer

+ X₃ kJ mol^{– 1}

Answer

– X₄ kJ mol^{– 1}

Answer

+ X₁kJ mol^{– 1}

Question 17

Given that bond energy of H–H and Cl–Cl is 430 kJ mol^–1 and 240 kJ mol^–1 respectively and ΔH_f for HCl is - 90 kJ mol^–1, bond enthalpy of HCl is: [2007]

Accepted Answer

425 kJ mol–1

Answer

380 kJ mol–1

Answer

245 kJ mol–1

Answer

290 kJ mol–1

Question 18

Which of the following are not state functions? [2008]
(I) q + w
(II) q
(III) w
(IV) H - TS

Accepted Answer

(II) and (III)

Answer

(I) and (IV)

Answer

(II), (III) and (IV)

Answer

(I), (II) and (III)

Question 19

For the gas phase reaction, which of the following conditions is correct? [2008]
PCl₅(g) ⇌ PCl₃(g) + Cl₂(g)

Accepted Answer

ΔH > 0 and ΔS > 0

Answer

ΔH = 0 and ΔS < 0

Answer

ΔH < 0 and ΔS < 0

Answer

ΔH > 0 and ΔS < 0

Question 20

Bond dissociation enthalpy of H₂, Cl_2, and HCl are 434, 242, and 431 kJ mol^–1 respectively. Enthalpy of formation of HCl is: [2008]

Accepted Answer

– 93 kJmol^–1

Answer

93 kJ mol^–1

Answer

– 245 kJmol^–1

Answer

245 kJmol^–1

Question 21

The values of ΔH and ΔS for the reaction, C_(graphite) + CO_{2 (g)}→ 2CO_(g) are 170 kJ and 170 JK^–1, respectively. This reaction will be spontaneous at: [2009]

Accepted Answer

1110 K

Answer

910 K

Answer

510 K

Answer

710 K

Question 22

From the following bond energies: [2009]
H – H bond energy: 431.37 kJ mol^–1
C = C bond energy: 606.10 kJ mol^–1
C – C bond energy: 336.49 kJ mol^–1
C – H bond energy: 410.50 kJ mol^–1

Enthalpy for the reaction, will be:

Accepted Answer

–120.0 kJ mol^–1

Answer

– 243.6 kJ mol^–1

Answer

553.0 kJ mol^–1

Answer

1523.6 kJ mol^–1

Question 23

Standard entropies of X₂ , Y₂ and XY₃ are 60, 40 and 50 JK^–1mol^–1respectively. For the reaction
to be at equilibrium, the temperature should be: [2010]

Accepted Answer

750 K

Answer

1000 K

Answer

1250 K

Answer

500 K

Question 24

For vapor ization of water at 1 atmospheric pressure, the values of ΔH and ΔS are 40.63 kJmol^–1 and 108.8 JK^–1 mol^–1, respectively. The temperature when Gibbs energy change (ΔG) for this transformation will be zero, is: [2010]

Accepted Answer

373.4 K.

Answer

293.4 K

Answer

273.4 K

Answer

393.4 K

Question 25

Match List -I (Equations) with List-II (Type of processes) and select the correct option. [2010]

Options:

Accepted Answer

d

Answer

a

Answer

b

Answer

c

Question 26

The following two reactions are known : [2010]

The value of ΔH for the following reaction

Accepted Answer

+ 6.2 kJ

Answer

+ 10.3 kJ

Answer

– 43.3 kJ

Answer

– 10.3 kJ

Question 27

If the enthalpy change for the transition of liquid water to steam is 30 kJ mol^–1 at 27ºC, the entropy change for the process would be: [2011]

Accepted Answer

100J mol^–1 K^–1

Answer

10 J mol^–1 K^–1

Answer

1.0 J mol^–1 K^–1

Answer

0.1 J mol^–1 K^–1

Question 28

Enthalpy change for the reaction, 4H_(g) → 2H_{2 (g)} is - 869.6 kJ. The dissociation energy of H–H bond is: [2011]

Accepted Answer

+ 434.8 kJ

Answer

– 434.8 kJ

Answer

– 869.6 kJ

Answer

+ 217.4 kJ

Question 29

Consider the following processes :

[2011M]

Accepted Answer

– 175 kJ/mol

Answer

525 kJ/mol

Answer

– 325 kJ/mol

Answer

325 kJ/mol

Question 30

In which of the following reactions, standard entropy change (ΔS°) is positive and standard Gibb’s energy change (ΔG°) decreases sharply with increasing temperature? [2012]

Accepted Answer

Answer

Answer

Answer

31 Year NEET Previous Questions: Thermodynamics - 1 Free MCQ Practice Test

MCQ Practice Test & Solutions: 31 Year NEET Previous Year Questions: Thermodynamics - 1 (36 Questions)

What is the entropy change (in JK–1 mol–1) when one mole of ice is converted into water at 0º C? (The enthalpy change for the conversion of ice to liquid water is 6.0 kJ mol–1 at 0ºC) [2003]

The densities of graphite and diamond at 298 K are 2.25 and 3.31g cm–3, respectively. If the standard free energy difference (ΔGº) is equal to 1895 J mol–1, the pressure at which graphite will be transformed into diamond at 298 K is: [2003]

For which one of the following equations is ΔHºreact equal to ΔHfº for the product? [2003]

For the reaction C3H8(g) + 5O2(g) → 3CO2(g) + 4H2O(l) at constant temperature, ΔH – ΔE is: [2003]

If the bond energies of H-H, Br-Br, and HBr are 433, 192 and 364 kJ mol–1 respectively, the ΔH° for the reaction H2(g) + Br2(g) → 2HBr(g) is: [2004]

The standard enthalpy and standard entropy changes for the oxidation of ammonia at 298 K are -382.64 kJ mol–1 and -145.6 JK–1 mol–1, respectively. Standard Gibb's energy change for the same reaction at 298 K is: [2004]

Considering entropy(S) as a thermodynamic parameter, the criterion for the spontaneity of any process is: [2004]

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: (1L atm = 101.32 J) [2004]

The absolute enthalpy of neutralisation of the reaction: MgO (s) + 2HCl (aq) —→ MgCl2(aq) + H2O (l) will be:[2005]

A reaction occurs spontaneously if: [2005]

Which of the following pairs of a chemical reaction is certain to result in a spontaneous reaction? [2005]

The enthalpy of hydrogenation of cyclohexene is –119.5 kJ mol–1. If the resonance energy of benzene is –150.4 kJ mol–1, its enthalpy of hydrogenation would be: [2006]

The enthalpy and entropy change for the reaction Br2(l) + Cl2(g) → 2BrCl(g) are 30kJ mol–1 and 105 JK–1 mol–1 respectively.The temperature at which the reaction will be in equilibrium is: [2006]

Identify the correct statement for change of Gibbs energy for a system (ΔGsystem) at constant temperature and pressure: [2006]

Assume each reaction is carried out in an open container. For which reaction will ΔH = ΔE? [2006]

Consider the following reactions: [2007](i) (ii) (iii) (iv) Enthalpy of formation of H2O (l) is

Given that bond energy of H–H and Cl–Cl is 430 kJ mol–1 and 240 kJ mol–1 respectively and ΔHf for HCl is - 90 kJ mol–1, bond enthalpy of HCl is: [2007]

Which of the following are not state functions? [2008] (I) q + w (II) q (III) w (IV) H - TS

For the gas phase reaction, which of the following conditions is correct? [2008] PCl5(g) ⇌ PCl3​(g) + Cl2​(g)

Bond dissociation enthalpy of H2, Cl2, and HCl are 434, 242, and 431 kJ mol–1 respectively. Enthalpy of formation of HCl is: [2008]

The values of ΔH and ΔS for the reaction, C(graphite) + CO2 (g) → 2CO(g) are 170 kJ and 170 JK–1, respectively. This reaction will be spontaneous at: [2009]

From the following bond energies: [2009] H – H bond energy: 431.37 kJ mol–1 C = C bond energy: 606.10 kJ mol–1 C – C bond energy: 336.49 kJ mol–1 C – H bond energy: 410.50 kJ mol–1Enthalpy for the reaction, will be:

Standard entropies of X2 , Y2 and XY3 are 60, 40 and 50 JK–1mol–1 respectively. For the reaction to be at equilibrium, the temperature should be: [2010]

For vapor ization of water at 1 atmospheric pressure, the values of ΔH and ΔS are 40.63 kJmol–1 and 108.8 JK–1 mol–1, respectively. The temperature when Gibbs energy change (ΔG) for this transformation will be zero, is: [2010]

Match List -I (Equations) with List-II (Type of processes) and select the correct option. [2010]Options:

The following two reactions are known : [2010]The value of ΔH for the following reaction

If the enthalpy change for the transition of liquid water to steam is 30 kJ mol–1 at 27ºC, the entropy change for the process would be: [2011]

Enthalpy change for the reaction, 4H(g) → 2H2 (g) is - 869.6 kJ. The dissociation energy of H–H bond is: [2011]

Consider the following processes : [2011M]

In which of the following reactions, standard entropy change (ΔS°) is positive and standard Gibb’s energy change (ΔG°) decreases sharply with increasing temperature? [2012]

Chemistry Class 11

Chemistry Class 11

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