*
Marked Questions are having more than one correct option.1. In thermodynamics, a process is called reversible when - [JEE 2001, 1/35]
(A) surroundings and system change into each other (B) there is no boundary between system and surroundings (C) the surroundings are always in equilibrium with the system (D) the system changes into the surroundings spontaneously
2. Which one of the following statement is false : [JEE 2001, 1/35]
(A) work is a state function (B) temperature is a state function
(C) change in the state is completely defined when the initial and final states are specified (D) work appears at the boundary of the system.
3. 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, U = 30.0 L atm. The change in enthalpy (H) of the process in L atm is
-(A) 40.0 (B) 42.3 [JEE 2002, 3/90]
(C) 44.0 (D) not defined, because pressure is not constant
4. Two moles of a perfect gas undergo the following process : [JEE 2002, 5/60]
(a) a reversible isobaric expansion from (1.0 atm, 20.0 L) to (1.0 atm, 40.0 L).
(b) a reversible isochoric change of state from (1.0 atm, 40.0 L) to (0.5 atm, 40.0 L).
(c) a reversible isothermal compression from (0.5 atm, 40.0 L) to (1.0 atm, 20.0 L).
(i) Sketch with labels each of the processes on the same P-V diagram.
(ii) Calculate the total work (w) and the total heat change (q) involved in the above processes.
(iii) What will be the values of U, H and S for the overall process ?
5. Which of the following equation gives the values of heat of formation (Hf0) [JEE 2003, 3/84]
(A) C (diamond) + O2(g) CO2 (g) (B) 2
1 H2(g) + 2
1 F2(g) HF (g)
(C) N2 (g) + 3H2 (g) 2NH3 (g) (D) H2(g) + F2 (g) 2HF (g)
6. The molar heat capacity, Cv, of helium gas is 3/2 R and is independent of temperature. For hydrogen gas, Cv approaches 3/2 R at very low temperatures, equal 5/2 R at moderate temperatures and is higher than 5/2 R at high temperatures. Give a reason for the temperature dependence of Cv in case of hydrogen, in not more
than two or three sentences. [JEE 2003, 2/60]
7. 2 moles of ideal gas is expanded isothermally & reversibly from 1 litre to 10 litre. Find the enthalpy change
in kJ mol–1. [JEE 2004, 3/84]
(A) 0 (B) 11.7 (C) – 11.7 (D) 25
8. H = 30 kJ mol–1 , S = 75 J / k / mol. Find boiling temperature at 1 atm. [JEE 2004, 3/84]
(A) 400 K (B) 300 K (C) 150 K (D) 425 K
9. Spontaneous adsorption of a gas on a solid surface is exothermic process because [JEE 2004, 3/84]
(A) enthalpy of the system increases. (B) entropy increases.
(C) entropy decreases. (D) free energy change increases.
10. There is 1 mol liquid (molar volume 100 ml) in an adiabatic container initial, pressure being 1 bar Now the pressure is steeply increased to 100 bar, and the volume decreased by 1 ml under constant pressure of 100 bar. Calculate H and E. [Given 1 bar = 105 N/m2] [JEE 2004, 2/60]
11. For the reaction : N2O4(g) 2NO2 (g)
(i) In a mixture of 5 mol NO2 and 5 mol N2O4 and pressure of 20 bar. Calculate the value of G for the reaction.
Given Gf° (NO2) = 50 kJ / mol, Gf° (N2O4) = 100 kJ / mol and T = 298 K.
(ii) Predict the direction in which the reaction will shift, in order to attain equilibrium
12. One mole of an ideal monoatomic gas at temperature T and volume 1L expands to 2L against a constant external pressure of one atm under adiabatic conditions, then final temperature of gas will be :
[JEE 2005, 3/84]
(A) T +
0821 . 0 3
2
(B) T –
0821 . 0 3
2
(C) 5/3 1
2 T
(D) 5/3 1
2 T
13. The ratio of P to V at any instant is constant and is equal to 1, for a monoatomic ideal gas under going a process. What is the molar heat capacity of the gas. [JEE 2006, 3/184]
(A) 2 R
3 (B)
2 R
4 (C)
2 R
5 (D) 0
14. The direct conversion of A to B is difficult, hence it is carried out by the following shown path:
S(A C) = 50 ; S(C D) = 30; S(B D) = – 20
The entropy change for the process A B is [JEE 2006, 3/184]
(A) 100 (B) – 60 (C) – 100 (D) + 60
15. The given reaction
2CO + O2 2CO2 H = – 560 kJ 2moles 1 mole
is carried and in one litre container, if the pressure in the container gets changes from 70 atm to 40 atm as reaction gets completed. Calculate U of the reaction. [1L atm = 0.1 kJ] [JEE 2006, 6/184]
16. The value of log10K for a reaction A B is : (Given : rH298K = –54.07 kJ mol–1, rS298K = 10 JK–1 mol–1 and R = 8.314 JK–1 mol–1 ; 2.303 × 8.314 × 298 = 5705) [JEE 2007, 3/162]
(A) 5 (B) 10 (C) 95 (D) 100
17. For the process H2O() (1 bar, 373 K) H2O(g) (1 bar, 373 K), the correct set of thermodynamic parameters
is : [JEE 2007, 3/162]
(A) G = 0, S = +ve (B) G = 0, S = –ve (C) G = +ve, S = 0 (D) G = –ve, S = +ve 18. STATEMENT-1 : For every chemical reaction at equilibrium, standard Gibbs energy of reaction is zero.
STATEMENT-2 : At constant temperature and pressure, chemical reactions are spontaneous in the direction
of decreasing Gibbs energy. [JEE 2008, 3/163]
(A) Statement-1 is True, Statement-2 is True; Statement-2 is a correct explanation for Statement-1.
(B) Statement-1 is True, Statement-2 is True; Statement-2 is NOT a correct explanation for Statement-1 (C) Statement-1 is True, Statement-2 is False
(D) Statement-1 is False, Statement-2 is True
19. STATEMENT-1 : There is a natural asymmetry between converting work to heat and converting heat to work.
STATEMENT-2 : No process is possible in which the sole result is the absorption of heat form a reservoir and
its complete conversion into work. [JEE 2008, 3/163]
(A) Statement-1 is True, Statement-2 is True; Statement-2 is a correct explanation for Statement-1.
(B) Statement-1 is True, Statement-2 is True; Statement-2 is NOT a correct explanation for Statement-1 (C) Statement-1 is True, Statement-2 is False
(D) Statement-1 is False, Statement-2 is True
20.* Among the following, the state function(s) is(are) : [JEE 2009, 4/160]
(A) Internal energy (B) Irreversible expansion work
(C) Reversible expansion work (D) Molar enthalpy
21. In a constant volume calorimeter, 3.5 g of a gas with molecular weight 28 was burnt in excess oxygen at 298.0 K. The temperature of the calorimeter was found to increases from 298.0 K to 298.45 K due to the combustion process. Given that the heat capacity of the calorimeter is 2.5 kJ K–1, the numerical value for the enthalpy of combustion of the gas in kJ mol–1 is. [JEE 2009, 4/160]
22. The species which by definition has ZERO standard molar enthalpy of formation at 298 K is :
[JEE 2010, 3/163]
(A) Br2(g) (B) Cl2(g) (C) H2O(g) (D) CH4(g)
23. The bond energy (in kcal mol–1) of a C–C single bond is approximately : [JEE 2010, 3/163]
(A) 1 (B) 10 (C) 100 (D) 1000
24.* Among the following, the intensive property is (properties are) : [JEE 2010, 3/163]
(A) molar conductivity (B) electromotive force (C) resistance (D) heat capacity
25. One mole of an ideal gas is taken from a and b along two paths denoted by the solid and the dashed lines as shown in the graph below. If the work done along the solid line path is ws and that along the dotted line path is wd, then the integer closest to the ratio wd / ws is : [JEE 2010, 3/163]
26. Match the transformations in column I with appropriate options in column II. [JEE 2011, 8/240]
Column-I Column-II
(A) CO2(s) CO2(g) (p) phase transition (B) CaCO3(s) CaO(s) + CO2(g) (q) allotropic change
(C) 2H• H2(g) (r) H is positive
(D) P(white, solid) P(red, solid) (s) S is positive (t) S is negative
27. For an ideal gas, consider only P-V work in going from an initial state X to the final state Z. The final state Z can be reached by either of the two paths shown in the figure. Which of the following choice(s) is (are) correct? [Take S as change in entropy and w as work done] [JEE 2012, 4/198]
(A) Sx z = Sx y + Sy z (B) wx z = wx y + wy z
(C) w = w (D) S = S
28. Using the data provided, calculate the multiple bond energy (kJ mol–1) of a C C bond in C2H2. That energy is (take the bond energy of a C – H bond as 350 kJ mol–1) [JEE 2012, 3/198]
2C(s) + H2(g) C2H2(g) H = 225 kJ mol–1 2C(s) 2C(g) H = 1410 kJ mol–1 H2(g) 2H(g) H = 330 kJ mol–1
(A) 1165 (B) 837 (C) 865 (D) 815
29. The reversible expansion of an ideal gas under adiabatic and isothermal conditions is shown in the figure.
Which of the following statements(s) is (are) correct ? [JEE 2012, 4/198]
(A) T1 = T2 (B) T3 > T1
(C) wisothermal > wadiabatic (D) Uisothermal > Uadiabatic Paragraph for Question Nos. 30 to 31
A fixed mass 'm' of a gas is subjected to transformation of states from K to L to M to N and back to K as shown in the figure.
30. The pair of isochoric processes among the transformation of states is : [JEE Advanced 2013]
(A) K to L and L to M (B) L to M and N to K (C) L to M and M to N (D) M to N and N to K 31. The succeeding operations that enable this transformation of states, are : [JEE Advanced 2013]
(A) Heating, cooling, heating, cooling (B) Cooling, heating, cooling, heating (C) Heating, cooling, cooling, heating (D) Cooling, heating, heating, cooling