Quiz - chemistry - Thermodynamics-PYQ

Q1. Which of the following are not state functions?
(I) q + w (II) q
(III) w (IV) H – TS Source: orcusprep.in

NEET 2008

easy

(I), (II) and (III)

(II) and (III)

(I) and (IV)

(II), (III) and (IV)

Q2. In a closed insulated container a liquid is stirred with a paddle to increase the temperature, which of the following is true? Source: orcusprep.in

NEET 2002

medium

\( \Delta E = W \neq 0, q = 0 \)

\( \Delta E = W = q \neq 0 \)

\( \Delta E = 0, W = q \neq 0 \)

\( W = 0, \Delta E = q \neq 0 \)

Q3. Which of the following is the correct equation? Source: orcusprep.in

NEET 1996

easy

\( \Delta U = \Delta W + \Delta Q \)

\( \Delta U = \Delta Q - W \)

\( \Delta W = \Delta U + \Delta Q \)

None of these

Q4. The correct option for free expansion of an ideal gas under adiabatic condition is Source: orcusprep.in

NEET 2020

easy

\( q = 0, \Delta T = 0 \) and \( w = 0 \)

\( q = 0, \Delta T < 0 \) and \( w > 0 \)

\( q < 0, \Delta T = 0 \) and \( w = 0 \)

\( q > 0, \Delta T > 0 \) and \( w > 0 \)

Q5. Under isothermal conditions, a gas at 300 K expands from 0.1 L to 0.25 L against a constant external pressure of 2 bar. The work done by the gas is Source: orcusprep.in

NEET 2019

easy

30 J

–30 J

5 kJ

25 J

Q6. Reversible expansion of an ideal gas under isothermal and adiabatic conditions are as shown in the figure.
AB → Isothermal expansion
AC → Adiabatic expansion
Which of the following options is not correct? Source: orcusprep.in

NEET 2019 (Odisha)

hard

\( \Delta S_{isothermal} > \Delta S_{adiabatic} \)

\( T_{A} = T_{B} \)

\( W_{isothermal} > W_{adiabatic} \)

\( T_{C} > T_{A} \)

Q7. An ideal gas expands isothermally from \( 10^{-3} m^{3} \) to \( 10^{-2} m^{3} \) at 300 K against a constant pressure of \( 10^{5} N m^{-2} \). The work done on the gas is Source: orcusprep.in

NEET 2019 (Odisha)

easy

+270 kJ

–900 J

+900 kJ

–900 kJ

Q8. A gas is allowed to expand in a well insulated container against a constant external pressure of 2.5 atm from an initial volume of 2.50 L to a final volume of 4.50 L. The change in internal energy \( \Delta U \) of the gas in joules will be Source: orcusprep.in

NEET 2017

easy

–500 J

–505 J

+505 J

1136.25 J

Q9. Equal volumes of two monatomic 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 Source: orcusprep.in

NEET 2012

medium

0.83

1.50

3.3

1.67

Q10. Which of the following is correct option for free expansion of an ideal gas under adiabatic condition? Source: orcusprep.in

NEET 2011

easy

\( q = 0, \Delta T \neq 0, w = 0 \)

\( q \neq 0, \Delta T = 0, w = 0 \)

\( q = 0, \Delta T = 0, w = 0 \)

\( q = 0, \Delta T < 0, w \neq 0 \)

Q11. Three moles of an ideal gas expanded spontaneously into vacuum. The work done will be Source: orcusprep.in

NEET 2010 (Mains)

easy

infinite

3 Joules

9 Joules

zero.

Q12. Assume each reaction is carried out in an open container. For which reaction will \( \Delta H = \Delta E \)? Source: orcusprep.in

NEET 2006

easy

\( 2CO(g) + O_{2}(g) \rightarrow 2CO_{2}(g) \)

\( H_{2}(g) + Br_{2}(g) \rightarrow 2HBr(g) \)

\( C(s) + 2H_{2}O(g) \rightarrow 2H_{2}(g) + CO_{2}(g) \)

\( PCl_{5}(g) \rightarrow PCl_{3}(g) + Cl_{2}(g) \)

Q13. The work done during the expansion of a gas from a volume of \( 4 \text{ dm}^{3} \) to \( 6 \text{ dm}^{3} \) against a constant external pressure of 3 atm is (1 L atm = 101.32 J) Source: orcusprep.in

NEET 2004

easy

– 6 J

– 608 J

+ 304 J

– 304 J

Q14. For the reaction,\( C_{3}H_{8}(g) + 5O_{2}(g) \rightarrow 3CO_{2}(g) + 4H_{2}O(l) \) at constant temperature, \( \Delta H - \Delta E \) is Source: orcusprep.in

NEET 2003

easy

\( + RT \)

\( -3RT \)

\( +3RT \)

\( -RT \)

Q15. The molar heat capacity of water at constant pressure, \( C_{p} \), is \( 75 \text{ J K}^{-1} \text{ mol}^{-1} \). 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 Source: orcusprep.in

NEET 2003

easy

1.2 K

2.4 K

4.8 K

6.6 K

Q16. 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? Source: orcusprep.in

NEET 2001

easy

q = w = 500 J, \( \Delta E \) = 0

q = \( \Delta E \) = 500 J, w = 0

q = w = 500 J, \( \Delta E \) = 0

\( \Delta E \) = 0, q = w = –500 J

Q17. For the reaction,\( C_{2}H_{5}OH(l) + 3O_{2}(g) \rightarrow 2CO_{2}(g) + 3H_{2}O(l) \) which one is true? Source: orcusprep.in

NEET 2000

easy

\( \Delta H = \Delta E - RT \)

\( \Delta H = \Delta E + RT \)

\( \Delta H = \Delta E + 2RT \)

\( \Delta H = \Delta E - 2RT \)

Q18. In an endothermic reaction, the value of \( \Delta H \) is Source: orcusprep.in

NEET 1999

easy

negative

positive

zero

constant.

Q19. One mole of an ideal gas at 300 K is expanded isothermally from an initial volume of 1 litre to 10 litres. The \( \Delta E \) for this process is
(R = \( 2 \text{ cal mol}^{-1} \text{ K}^{-1} \)) Source: orcusprep.in

NEET 1998

easy

1381.1 cal

zero

163.7 cal

9 L atm

Q20. During isothermal expansion of an ideal gas, its Source: orcusprep.in

NEET 1994, 1991

easy

internal energy increases

enthalpy decreases

enthalpy remains unaffected

enthalpy reduces to zero.

Q21. For the reaction, \( N_{2} + 3H_{2} \leftrightarrows 2NH_{3} \), \( \Delta H = ? \) Source: orcusprep.in

NEET 1991

easy

\( \Delta E + 2RT \)

\( \Delta E - 2RT \)

\( \Delta H = RT \)

\( \Delta E - RT \)

Q22. If \( \Delta H \) is the change in enthalpy and \( \Delta E \), the change in internal energy accompanying a gaseous reaction, then Source: orcusprep.in

NEET 1990

medium

\( \Delta H \) is always greater than \( \Delta E \)

\( \Delta H < \Delta E \) only if the number of moles of the products is greater than the number of moles of the reactants

\( \Delta H \) is always less than \( \Delta E \)

\( \Delta H < \Delta E \) only if the number of moles of products is less than the number of moles of the reactants.

Q23. Three thermochemical equations are given below :
(i) \( C(graphite) + O_{2}(g) \rightarrow CO_{2}(g) \); \( \Delta_{r}H^{\circ} = x \text{ kJ mol}^{-1} \)
(ii) \( C(graphite) + \frac{1}{2}O_{2}(g) \rightarrow CO(g) \); \( \Delta_{r}H^{\circ} = y \text{ kJ mol}^{-1} \)
(iii) \( CO(g) + \frac{1}{2}O_{2}(g) \rightarrow CO_{2}(g) \); \( \Delta_{r}H^{\circ} = z \text{ kJ mol}^{-1} \)
Based on the above equations, find out which of the relationship given below is correct. Source: orcusprep.in

NEET 2013 (Karnataka)

easy

z = x + y

x = y + z

y = 2z – x

x = y – z

Q24. Standard enthalpy of vaporisation \( \Delta_{vap}H^{\circ} \) for water at 100°C is \( 40.66 \text{ kJ mol}^{-1} \). The internal energy of vaporisation of water at 100°C (in \( \text{kJ mol}^{-1} \)) is
(Assume water vapour to behave like an ideal gas) Source: orcusprep.in

NEET 2012

easy

+37.56

– 43.76

+ 43.76

+ 40.66

Q25. Consider the following processes :
\( \Delta H \) (kJ/mol)
1. \( \frac{1}{2}A \rightarrow B \) +150
2. \( 3B \rightarrow 2C + D \) –125
3. \( E + A \rightarrow 2D \) +350
For \( B + D \rightarrow E + 2C \), \( \Delta H \) will be Source: orcusprep.in

NEET 2011 (Mains)

hard

525 kJ/mol

–175 kJ/mol

–325 kJ/mol

325 kJ/mol

Q26. The following two reactions are known
1. \( Fe_{2}O_{3}(s) + 3CO(g) \rightarrow 2Fe(s) + 3CO_{2}(g) \); \( \Delta H = –26.8 \text{ kJ} \)
2. \( FeO(s) + CO(g)\rightarrow Fe(s) + CO_{2}(g) \); \( \Delta H = – 16.5 \text{ kJ} \)
The value of \( \Delta H \) for the following reaction \( Fe_{2}O_{3}(s) + CO(g) \rightarrow 2FeO(s) + CO_{2}(g) \) is Source: orcusprep.in

NEET 2010 (Mains)

medium

+ 10.3 kJ

– 43.3 kJ

– 10.3 kJ

+ 6.2 kJ

Q27. For which one of the following equations is \( \Delta H^{\circ}_{reaction} \) equal to \( \Delta H^{\circ}_{f} \) for the product? Source: orcusprep.in

NEET 2003

easy

\( N_{2}(g) + O_{3}(g) \rightarrow N_{2}O_{3}(g) \)

\( CH_{4}(g) + 2Cl_{2}(g) \rightarrow CH_{2}Cl_{2}(l) + 2HCl(g) \)

\( Xe(g) + 2F_{2}(g) \rightarrow XeF_{4}(g) \)

\( 2CO(g) + O_{2}(g) \rightarrow 2CO_{2}(g) \)

Q28. Heat of combustion \( \Delta H \) for \( C(s) \), \( H_{2}(g) \) and \( CH_{4}(g) \) are –94, –68 and –213 kcal/mol, then \( \Delta H \) for \( C(s) + 2H_{2}(g) \rightarrow CH_{4}(g) \) is Source: orcusprep.in

NEET 2002

medium

–17 kcal

–111 kcal

–170 kcal

–85 kcal

Q29. Change in enthalpy for reaction, \( 2H_{2}O_{2}(l) \rightarrow 2H_{2}O(l) + O_{2}(g) \) if heat of formation of \( H_{2}O_{2}(l) \) and \( H_{2}O(l) \) are –188 and –286 kJ/mol respectively, is Source: orcusprep.in

NEET 2001

easy

–196 kJ/mol

+196 kJ/mol

+948 kJ/mol

–948 kJ/mole

Q30. Enthalpy of \( CH_{4} + \frac{1}{2}O_{2} \rightarrow CH_{3}OH \) is negative. If enthalpy of combustion of \( CH_{4} \) and \( CH_{3}OH \) are x and y respectively, then which relation is correct? Source: orcusprep.in

NEET 2001

hard

x > y

x < y

x = y

x \( \geq \) y

Q31. In the reaction : \( S + \frac{3}{2}O_{2} \rightarrow SO_{3} + 2x \) kcal and \( SO_{2} + \frac{1}{2}O_{2} \rightarrow SO_{3} + y \) kcal, the heat of formation of \( SO_{2} \) is Source: orcusprep.in

NEET 1999

medium

\( (2x + y) \)

\( (x - y) \)

\( (x + y) \)

\( (2x - y) \)

Q32. Given that \( C + O_{2} \rightarrow CO_{2} \), \( \Delta H^{\circ} = - x \text{ kJ} \) and \( 2CO + O_{2} \rightarrow 2CO_{2} \), \( \Delta H^{\circ} = - y \text{ kJ} \). The enthalpy of formation of carbon monoxide will be Source: orcusprep.in

NEET 1997

medium

\( \frac{y-x}{2} \)

\( 2x - y \)

\( y - 2x \)

\( \frac{2x-y}{2} \)

Q33. If enthalpies of formation for \( C_{2}H_{4}(g) \), \( CO_{2}(g) \) and \( H_{2}O(l) \) at \( 25^{\circ}C \) and 1 atm pressure are 52, – 394 and – 286 kJ/mol respectively, then enthalpy of combustion of \( C_{2}H_{4}(g) \) will be Source: orcusprep.in

NEET 1995

medium

+ 141.2 kJ/mol

+ 1412 kJ/mol

– 141.2 kJ/mol

– 1412 kJ/mol

Q34. The bond dissociation energies of \( X_{2} \), \( Y_{2} \) and \( XY \) are in the ratio of 1 : 0.5 : 1. \( \Delta H \) for the formation of \( XY \) is –200 kJ \( \text{mol}^{-1} \). The bond dissociation energy of \( X_{2} \) will be Source: orcusprep.in

NEET 2018

hard

200 kJ \( \text{mol}^{-1} \)

100 kJ \( \text{mol}^{-1} \)

800 kJ \( \text{mol}^{-1} \)

400 kJ \( \text{mol}^{-1} \)

Q35. The heat of combustion of carbon to \( CO_{2} \) is –393.5 kJ/mol. The heat released upon formation of 35.2 g of \( CO_{2} \) from carbon and oxygen gas is Source: orcusprep.in

NEET 2015

easy

+ 315 kJ

– 630 kJ

– 3.15 kJ

– 315 kJ

Q36. When 5 litres of a gas mixture of methane and propane is perfectly combusted at \( 0^{\circ}C \) and 1 atmosphere, 16 litres of oxygen at the same temperature and pressure is consumed. The amount of heat released from this combustion in kJ (\( \Delta H_{comb} \) (\( CH_{4} \)) = \( -890 \text{ kJ mol}^{-1} \), \( \Delta H_{comb.} \) (\( C_{3}H_{8} \)) = \( -2220 \text{ kJ mol}^{-1} \)) is Source: orcusprep.in

NEET 2013 (Karnataka)

hard

38

317

477

32

Q37. Enthalpy change for the reaction, \( 4H(g) \rightarrow 2H_{2}(g) \) is –869.6 kJ. The dissociation energy of H – H bond is Source: orcusprep.in

NEET 2011

easy

– 434.8 kJ

– 869.6 kJ

+ 434.8 kJ

+ 217.4 kJ

Q38. From the following bond energies :
H — H bond energy : \( 431.37 \text{ kJ mol}^{-1} \)
C == C bond energy : \( 606.10 \text{ kJ mol}^{-1} \)
C — C bond energy : \( 336.49 \text{ kJ mol}^{-1} \)
C — H bond energy : \( 410.50 \text{ kJ mol}^{-1} \)
Enthalpy for the reaction, \( C_{2}H_{4}(g) + H_{2}(g) \rightarrow C_{2}H_{6}(g) \) will be Source: orcusprep.in

NEET 2009

medium

– 243.6 kJ \( \text{mol}^{-1} \)

– 120.0 kJ \( \text{mol}^{-1} \)

553.0 kJ \( \text{mol}^{-1} \)

1523.6 kJ \( \text{mol}^{-1} \)

Q39. Bond dissociation enthalpy of \( H_{2} \), \( Cl_{2} \) and HCl are 434, 242 and 431 kJ \( \text{mol}^{-1} \) respectively. Enthalpy of formation of HCl is Source: orcusprep.in

NEET 2008

easy

–93 kJ \( \text{mol}^{-1} \)

245 kJ \( \text{mol}^{-1} \)

93 kJ \( \text{mol}^{-1} \)

–245 kJ \( \text{mol}^{-1} \)

Q40. Consider the following reactions :
(i) \( H^{+}(aq) + OH^{-}(aq) = H_{2}O(l) \), \( \Delta H = -X_{1} \text{ kJ mol}^{-1} \)
(ii) \( H_{2}(g) + \frac{1}{2}O_{2}(g) = H_{2}O(l) \), \( \Delta H = -X_{2} \text{ kJ mol}^{-1} \)
(iii) \( CO_{2}(g) + H_{2}(g) = CO(g) + H_{2}O(l) \), \( \Delta H = -X_{3} \text{ kJ mol}^{-1} \)
(iv) \( C_{2}H_{2}(g) + \frac{5}{2}O_{2}(g) = 2CO_{2}(g) + H_{2}O(l) \), \( \Delta H = +X_{4} \text{ kJ mol}^{-1} \)
Enthalpy of formation of \( H_{2}O(l) \) is Source: orcusprep.in

NEET 2007

easy

\( +X_{3} \text{ kJ mol}^{-1} \)

\( -X_{4} \text{ kJ mol}^{-1} \)

\( +X_{1} \text{ kJ mol}^{-1} \)

\( -X_{2} \text{ kJ mol}^{-1} \)

Q41. Given that bond energies of H – H and Cl – Cl are 430 kJ \( \text{mol}^{-1} \) and 240 kJ \( \text{mol}^{-1} \) respectively and \( \Delta H_{f} \) for HCl is –90 kJ \( \text{mol}^{-1} \), bond enthalpy of HCl is Source: orcusprep.in

NEET 2007

medium

380 kJ \( \text{mol}^{-1} \)

425 kJ \( \text{mol}^{-1} \)

245 kJ \( \text{mol}^{-1} \)

290 kJ \( \text{mol}^{-1} \)

Q42. The absolute enthalpy of neutralisation of the reaction : \( MgO(s) + 2HCl(aq) \rightarrow MgCl_{2}(aq) + H_{2}O(l) \) will be Source: orcusprep.in

NEET 2005

medium

–57.33 kJ \( \text{mol}^{-1} \)

greater than –57.33 kJ \( \text{mol}^{-1} \)

less than –57.33 kJ \( \text{mol}^{-1} \)

57.33 kJ \( \text{mol}^{-1} \)

Q43. If the bond energies of H–H, Br–Br, and H–Br are 433, 192 and 364 kJ \( \text{mol}^{-1} \) respectively, the \( \Delta H^{\circ} \) for the reaction \( H_{2}(g) + Br_{2}(g) \rightarrow 2HBr(g) \) is Source: orcusprep.in

NEET 2004

easy

–261 kJ

+103 kJ

+261 kJ

–103 kJ

Q44. For the reaction, \( 2Cl(g) \rightarrow Cl_{2}(g) \), the correct option is Source: orcusprep.in

NEET 2020

easy

\( \Delta_{r}H > 0 \) and \( \Delta_{r}S > 0 \)

\( \Delta_{r}H > 0 \) and \( \Delta_{r}S < 0 \)

\( \Delta_{r}H < 0 \) and \( \Delta_{r}S > 0 \)

\( \Delta_{r}H < 0 \) and \( \Delta_{r}S < 0 \)

Q45. In which case change in entropy is negative? Source: orcusprep.in

NEET 2019

easy

\( 2H(g) \rightarrow H_{2}(g) \)

Evaporation of water

Expansion of a gas at constant temperature

Sublimation of solid to gas

Q46. For a given reaction, \( \Delta H = 35.5 \text{ kJ mol}^{-1} \) and \( \Delta S = 83.6 \text{ J K}^{-1} \text{ mol}^{-1} \). The reaction is spontaneous at (Assume that \( \Delta H \) and \( \Delta S \) do not vary with temperature.) Source: orcusprep.in

NEET 2017

easy

T > 425 K

all temperatures

T > 298 K

T < 425 K

Q47. For a sample of perfect gas when its pressure is changed isothermally from \( p_{i} \) to \( p_{f} \), the entropy change is given by Source: orcusprep.in

NEET-II 2016

medium

\( \Delta S = nR \ln(\frac{p_{f}}{p_{i}}) \)

\( \Delta S = nR \ln(\frac{p_{i}}{p_{f}}) \)

\( \Delta S = nRT \ln(\frac{p_{f}}{p_{i}}) \)

\( \Delta S = RT \ln(\frac{p_{i}}{p_{f}}) \)

Q48. The correct thermodynamic conditions for the spontaneous reaction at all temperatures is Source: orcusprep.in

NEET-I 2016

easy

\( \Delta H < 0 \) and \( \Delta S > 0 \)

\( \Delta H < 0 \) and \( \Delta S < 0 \)

\( \Delta H < 0 \) and \( \Delta S = 0 \)

\( \Delta H > 0 \) and \( \Delta S < 0 \)

Q49. Consider the following liquid-vapour equilibrium.
Liquid \( \rightleftharpoons \) Vapour
Which of the following relations is correct? Source: orcusprep.in

NEET-I 2016

hard

\( \frac{d \ln P}{dT} = -\frac{\Delta H_{v}}{T^{2}} \)

\( \frac{d \ln P}{dT} = \frac{\Delta H_{v}}{RT^{2}} \)

\( \frac{d \ln G}{dT} = \frac{\Delta H_{v}}{RT^{2}} \)

\( \frac{d \ln P}{dT} = -\frac{\Delta H_{v}}{RT} \)

Q50. Which of the following statements is correct for the spontaneous adsorption of a gas? Source: orcusprep.in

NEET 2014

medium

\( \Delta S \) is negative and, therefore \( \Delta H \) should be highly positive.

\( \Delta S \) is negative and therefore, \( \Delta H \) should be highly negative.

\( \Delta S \) is positive and therefore, \( \Delta H \) should be negative.

\( \Delta S \) is positive and therefore, \( \Delta H \) should also be highly positive.

Q51. For the reaction, \( X_{2}O_{4}(l) \rightleftharpoons 2XO_{2}(g) \)
\( \Delta U = 2.1 \text{ kcal} \), \( \Delta S = 20 \text{ cal K}^{-1} \) at 300 K
Hence, \( \Delta G \) is Source: orcusprep.in

NEET 2014

hard

2.7 kcal

– 2.7 kcal

9.3 kcal

– 9.3 kcal

Q52. A reaction having equal energies of activation for forward and reverse reactions has Source: orcusprep.in

NEET 2013

easy

\( \Delta H = 0 \)

\( \Delta H = \Delta G = \Delta S = 0 \)

\( \Delta S = 0 \)

\( \Delta G = 0 \)

Q53. In which of the following reactions, standard reaction entropy change (\( \Delta S^{\circ} \)) is positive and standard Gibbs energy change (\( \Delta G^{\circ} \)) decreases sharply with increasing temperature? Source: orcusprep.in

NEET 2012

medium

\( C(\text{graphite}) + \frac{1}{2}O_{2}(g) \rightarrow CO(g) \)

\( CO(g) + \frac{1}{2}O_{2}(g) \rightarrow CO_{2}(g) \)

\( Mg(s) + \frac{1}{2}O_{2}(g) \rightarrow MgO(s) \)

\( \frac{1}{2}C(\text{graphite}) + \frac{1}{2}O_{2}(g) \rightarrow \frac{1}{2}CO_{2}(g) \)

Q54. The enthalpy of fusion of water is 1.435 kcal/mol. The molar entropy change for the melting of ice at \( 0^{\circ}C \) is Source: orcusprep.in

NEET 2012

easy

10.52 cal/(mol K)

21.04 cal/(mol K)

5.260 cal/(mol K)

0.526 cal/(mol K)

Q55. If the enthalpy change for the transition of liquid water to steam is 30 kJ \( \text{mol}^{-1} \) at \( 27^{\circ}C \), the entropy change for the process would be Source: orcusprep.in

NEET 2011

easy

10 J \( \text{mol}^{-1} \text{ K}^{-1} \)

1.0 J \( \text{mol}^{-1} \text{ K}^{-1} \)

0.1 J \( \text{mol}^{-1} \text{ K}^{-1} \)

100 J \( \text{mol}^{-1} \text{ K}^{-1} \)

Q56. Standard entropies of \( X_{2} \), \( Y_{2} \) and \( XY_{3} \) are 60, 40 and 50 J \( \text{K}^{-1} \text{mol}^{-1} \) respectively. For the reaction \( \frac{1}{2}X_{2} + \frac{3}{2}Y_{2} \rightleftharpoons XY_{3} \), \( \Delta H = -30 \text{ kJ} \), to be at equilibrium, the temperature should be Source: orcusprep.in

NEET 2010

medium

750 K

1000 K

1250 K

500 K

Q57. For vaporization of water at 1 atmospheric pressure, the values of \( \Delta H \) and \( \Delta S \) are 40.63 kJ \( \text{mol}^{-1} \) and 108.8 J \( \text{K}^{-1} \text{mol}^{-1} \), respectively. The temperature when Gibbs’ energy change (\( \Delta G \)) for this transformation will be zero, is Source: orcusprep.in

NEET Mains 2010

easy

273.4 K

393.4 K

373.4 K

293.4 K

Q58. The values of \( \Delta H \) and \( \Delta S \) for the reaction, \( C(\text{graphite}) + CO_{2}(g) \rightarrow 2CO(g) \) are 170 kJ and 170 J \( \text{K}^{-1} \), respectively. This reaction will be spontaneous at Source: orcusprep.in

NEET 2009

easy

910 K

1110 K

510 K

710 K

Q59. For the gas phase reaction, \( PCl_{5}(g) \rightleftharpoons PCl_{3}(g) + Cl_{2}(g) \), which of the following conditions are correct? Source: orcusprep.in

NEET 2008

easy

\( \Delta H < 0 \) and \( \Delta S < 0 \)

\( \Delta H > 0 \) and \( \Delta S < 0 \)

\( \Delta H = 0 \) and \( \Delta S < 0 \)

\( \Delta H > 0 \) and \( \Delta S > 0 \)

Q60. Identify the correct statement for change of Gibbs’ energy for a system (\( \Delta G_{\text{system}} \)) at constant temperature and pressure. Source: orcusprep.in

NEET 2006

easy

If \( \Delta G_{\text{system}} < 0 \), the process is not spontaneous.

If \( \Delta G_{\text{system}} > 0 \), the process is spontaneous.

If \( \Delta G_{\text{system}} = 0 \), the system has attained equilibrium.

If \( \Delta G_{\text{system}} = 0 \), the system is still moving in a particular direction.

Q61. The enthalpy and entropy change for the reaction: \( Br_{2}(l) + Cl_{2}(g) \rightarrow 2BrCl(g) \) are 30 kJ \( \text{mol}^{-1} \) and 105 J \( \text{K}^{-1} \text{mol}^{-1} \) respectively. The temperature at which the reaction will be in equilibrium is Source: orcusprep.in

NEET 2006

easy

300 K

285.7 K

273 K

450 K

Q62. Which of the following pairs of a chemical reaction is certain to result in a spontaneous reaction? Source: orcusprep.in

NEET 2005

easy

Exothermic and increasing disorder

Exothermic and decreasing disorder

Endothermic and increasing disorder

Endothermic and decreasing disorder

Q63. A reaction occurs spontaneously if Source: orcusprep.in

NEET 2005

medium

\( T\Delta S < \Delta H \) and both \( \Delta H \) and \( \Delta S \) are +ve

\( T\Delta S > \Delta H \) and \( \Delta H \) is +ve and \( \Delta S \) is –ve

\( T\Delta S > \Delta H \) and both \( \Delta H \) and \( \Delta S \) are +ve

\( T\Delta S = \Delta H \) and both \( \Delta H \) and \( \Delta S \) are +ve

Q64. Standard enthalpy and standard entropy changes for the oxidation of ammonia at 298 K are –382.64 kJ \( \text{mol}^{-1} \) and –145.6 J \( \text{mol}^{-1} \), respectively. Standard Gibbs’ energy change for the same reaction at 298 K is Source: orcusprep.in

NEET 2004

easy

– 221.1 kJ \( \text{mol}^{-1} \)

– 339.3 kJ \( \text{mol}^{-1} \)

– 439.3 kJ \( \text{mol}^{-1} \)

– 523.2 kJ \( \text{mol}^{-1} \)

Q65. Considering entropy (S) as a thermodynamic parameter, the criterion for the spontaneity of any process is Source: orcusprep.in

NEET 2004

easy

\( \Delta S_{\text{system}} + \Delta S_{\text{surroundings}} > 0 \)

\( \Delta S_{\text{system}} - \Delta S_{\text{surroundings}} > 0 \)

\( \Delta S_{\text{system}} > 0 \) only

\( \Delta S_{\text{surroundings}} > 0 \) only.

Q66. What is the entropy change (in J \( \text{K}^{-1} \text{mol}^{-1} \)) when one mole of ice is converted into water at \( 0^{\circ}C \)? (The enthalpy change for the conversion of ice to liquid water is 6.0 kJ \( \text{mol}^{-1} \) at \( 0^{\circ}C \).) Source: orcusprep.in

NEET 2003

easy

20.13

2.013

2.198

21.98

Q67. The densities of graphite and diamond at 298 K are 2.25 and 3.31 g \( \text{cm}^{-3} \), respectively. If the standard free energy difference (\( \Delta G^{\circ} \)) is equal to 1895 J \( \text{mol}^{-1} \), the pressure at which graphite will be transformed into diamond at 298 K is Source: orcusprep.in

NEET 2003

hard

9.92 \( \times 10^{8} \) Pa

9.92 \( \times 10^{7} \) Pa

9.92 \( \times 10^{6} \) Pa

9.92 \( \times 10^{5} \) Pa

Q68. Unit of entropy is Source: orcusprep.in

NEET 2002

easy

J \( \text{K}^{-1} \text{mol}^{-1} \)

J \( \text{mol}^{-1} \)

\( \text{J}^{-1} \text{K}^{-1} \text{mol}^{-1} \)

J K \( \text{mol}^{-1} \)

Q69. 2 moles of ideal gas at \( 27^{\circ}C \) temperature is expanded reversibly from 2 lit. to 20 lit. Find entropy change. (R = 2 cal/mol K) Source: orcusprep.in

NEET 2002

easy

92.1

0

4

9.2

Q70. \( PbO_{2} \rightarrow PbO \); \( \Delta G_{298} < 0 \)
\( SnO_{2} \rightarrow SnO \); \( \Delta G_{298} > 0 \)
Most probable oxidation state of Pb and Sn will be. Source: orcusprep.in

NEET 2001

medium

\( Pb^{4+} \), \( Sn^{4+} \)

\( Pb^{4+} \), \( Sn^{2+} \)

\( Pb^{2+} \), \( Sn^{2+} \)

\( Pb^{2+} \), \( Sn^{4+} \)

Q71. Cell reaction is spontaneous when Source: orcusprep.in

NEET 2000

easy

\( \Delta G^{\circ} \) is negative

\( \Delta G^{\circ} \) is positive

\( \Delta E^{\circ}_{red} \) is positive

\( \Delta E^{\circ}_{red} \) is negative.

Q72. Identify the correct statement regarding entropy. Source: orcusprep.in

NEET 1998

easy

At absolute zero of temperature, the entropy of all crystalline substances is taken to be zero.

At absolute zero of temperature, the entropy of a perfectly crystalline substance is +ve.

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

At \( 0^{\circ}C \), the entropy of a perfectly crystalline substance is taken to be zero.

Q73. Following reaction occurring in an automobile
\( 2C_{8}H_{18}(g) + 25O_{2}(g) \rightarrow 16CO_{2}(g) + 18H_{2}O(g) \)
The sign of \( \Delta H \), \( \Delta S \) and \( \Delta G \) would be Source: orcusprep.in

NEET 1994

easy

–, +, +

+, +, –

+, –, +

–, +, –

Q74. Which amongst the following options is the correct relation between change in enthalpy and change in internal energy? Source: orcusprep.in

NEET 2023

easy

\( \Delta H - \Delta U = -\Delta nRT \)

\( \Delta H + \Delta U = \Delta nR \)

\( \Delta H = \Delta U - \Delta nRT \)

\( \Delta H = \Delta U + \Delta nRT \)

Q75. For irreversible expansion of an ideal gas under isothermal condition, the correct option is Source: orcusprep.in

NEET 2021

medium

\( \Delta U > 0, \Delta S_{\text{total}} > 0 \)

\( \Delta U = 0, \Delta S_{\text{total}} = 0 \)

\( \Delta U \neq 0, \Delta S_{\text{total}} \neq 0 \)

\( \Delta U = 0, \Delta S_{\text{total}} > 0 \)

Q76. In which of the following processes entropy increases?
A. A liquid evaporates to vapour.
B. Temperature of a crystalline solid lowered from 130 K to 0 K.
C. \( 2NaHCO_{3}(s) \rightarrow Na_{2}CO_{3}(s) + CO_{2}(g) + H_{2}O(g) \)
D. \( Cl_{2}(g) \rightarrow 2Cl(g) \)
Choose the correct answer from the options given below: Source: orcusprep.in

NEET 2024

easy

A and C

A, B and D

A, C and D

C and D

Q77. Consider the following reaction:
\( 2H_{2}(g) + O_{2}(g) \rightarrow 2H_{2}O(l) \); \( \Delta H = -483.64 \text{ kJ} \). What is the enthalpy change for decomposition of one mole of water? Source: orcusprep.in

NEET 2022

easy

120.9 kJ

241.82 kJ

18 kJ

100 kJ

Q78. Which one among the following is the correct option for right relationship between \( C_{p} \) and \( C_{v} \) for one mole of ideal gas? Source: orcusprep.in

NEET 2021

easy

\( C_{v} = RC_{p} \)

\( C_{p} + C_{v} = R \)

\( C_{p} - C_{v} = R \)

\( C_{p} = RC_{v} \)

Q79. Match the following? Source: orcusprep.in

NCERT

easy

1

2

3

4

Q80. Which of the following P-V curve represents maximum work done? Source: orcusprep.in

NCERT

easy

1

2

3

4

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Chemistry - Thermodynamics-PYQ

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Chemistry - Thermodynamics-PYQ

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