Thermodynamics

Arrange the following isothermal processes in order of the magnitude of the work (p − V) involved between states 1 and 2. Choose the correct option.

1. |wB| > |wA| > |wC| > |wD|
2. |wC| > |wD| > |wA| > |wB|
3. |wC| > |wD| > |wB| > |wA|
4. |wB| > |wA| > |wD| > |wC|

Consider the following data for the reaction X2(g) + Y2(g) 2XY(g) at 600 K. The rG (in kJ mol-1) for the reaction is : array|c|c|c| Compound & fH 600 K ( kJ mol-1) & S 600 K ( J mol-1 K-1) \ XY(g) & 42 & 200 \ X2(g) & 8 & 140 \ Y2(g) & 80 & 250 \ array

1. −21000
2. −10
3. −1000
4. −9.012

The correct order of molar heat capacities measured at 298 K and 1 bar is :

1. Copper(s) > Bromine(l) > Helium(g)
2. Bromine(l) > Copper(s) > Helium(g)
3. Helium(g) > Bromine(l) > Copper(s)
4. Helium(g) > Bromine(l) = Copper(s)

Given below are two statements : In the light of the above statements, choose the correct answer from the options given below

1. Both Statement I and Statement II are true
2. Both Statement I and Statement II are false
3. Statement I is true but Statement II is false
4. Statement I is false but Statement II is true

Consider the following data. (i) 2Al(s) + 6HCl(aq) Al2Cl6(aq) + 3H2(g) + 1200 kJ/mol (ii) H2(g) + Cl2(g) 2HCl(g) + 164 kJ/mol (iii) HCl(g) + aq HCl(aq) + 83 kJ/mol (iv) Al2Cl6(s) + aq Al2Cl6(aq) + 663 kJ/mol The enthalpy of formation of anhydrous solid Al2Cl6 is :

1. -648 kJ mol-1
2. -1350 kJ mol-1
3. -2002 kJ mol-1
4. -1527 kJ mol-1

Gas 'A' undergoes change from state 'X' to state 'Y'. In this process, the heat absorbed and work done by the gas is 10 J and 18 J respectively. Now gas is brought back to state 'X' by another process during which 6 J of heat is evolved. In the reverse process of 'Y' to 'X',

1. 18 J of the work is done by the gas 'A'.
2. 2 J of the work is done by the gas 'A'.
3. 12 J of the work is done on the gas 'A' by the surrounding.
4. 14 J of the work is done on the gas 'A' by the surrounding.

20.0 dm3 of an ideal gas 'X' at 600 K and 0.5 MPa undergoes isothermal reversible expansion until pressure of the gas is 0.2 MPa. Which of the following option is correct? (Given: 2 = 0.3010 and 5 = 0.6989)

1. w = -9.1 kJ, U = 0, H = 0, q = 9.1 kJ
2. w = 9.1 J, U = 9.1 J, H = 0; q = 0
3. w = -3.9 kJ, U = 0, H = 0; q = 3.9 kJ
4. w = +4.1 kJ, U = 0, H = 0; q = -4.1 kJ

The plot of 10 K vs 1T gives a straight line. The intercept and slope respectively are (where K is the equilibrium constant).

1. - S R2.303, H R2.303
2. - H 2.303R, S 2.303R
3. S 2.303R, - H 2.303R
4. 2.303R H , 2.303R S

The heats of atomisation of methane and ethane are 'x' kJ mol-1 and 'y' kJ mol-1 respectively. The longest wavelength ( ) of light capable of breaking the C-C bond can be expressed in SI unit as :

1. NA hc250(y - 6x)
2. NA hc (y - 6x4 )-1
3. hc1000 ( y - 6x4 )-1
4. NA hc250(4y - 6x)

A cup of water at 5 C (system) is placed in a microwave oven and the oven is turned on for one minute during which the water begins to boil. Which of the following options is true?

1. q = +ve, w = -ve, U = +ve
2. q = +ve, w = 0, U = -ve
3. q = +ve, w = -ve, U = -ve
4. q = -ve, w = -ve, U = -ve

Which of the following graphs between pressure 'p' versus volume 'V' represents the maximum work done?

1. [figure]
2. [figure]
3. [figure]
4. [figure]

Consider the following data : f H (methane, g) = -X kJ mol-1 Enthalpy of sublimation of graphite = Y kJ mol-1 Dissociation enthalpy of H2 = Z kJ mol-1 The bond enthalpy of C–H bond is given by :

1. X+Y+2Z4
2. X+Y+4Z2
3. -X+Y+Z4
4. X+Y+Z

Total enthalpy change for freezing of 1 mol of water at 10 C to ice at -10 C is (Given: fusH = x kJ/mol Cp[H2O(l)] = y J mol-1 K-1 Cp[H2O(s)] = z J mol-1 K-1)

1. -x-10y-10z
2. x-10y-10z
3. -10(100x+y+z)
4. 10(100x+y+z)

The hydration energies of K+ and Cl- are -x and -y kJ/mol respectively. If the lattice energy of KCl is -z kJ/mol, then the heat of solution of KCl is :

1. x + y + z
2. z - (x + y)
3. -z - (x + y)
4. x - y - z

The correct statement amongst the following is :

1. The standard state of a pure gas is the pure gas at a pressure of 1 bar and temperature 273 K.
2. f H 500 is zero for O2(g).
3. f H 298 is zero for O(g).
4. The term 'standard state' implies that the temperature is 0°C.

One mole of an ideal gas expands isothermally and reversibly from 10 dm3 to 20 dm3 at 300 K. U, q and work done in the process respectively are Given: R = 8.3 J K-1 mol-1 10 = 2.3 2 = 0.30 3 = 0.48

1. 0, 21.84 kJ, -1.726 J
2. 0, 21.84 kJ, 21.84 kJ
3. 0, 1.718 kJ, -1.718 kJ
4. 0, -17.18 kJ, 1.718 J

Let us consider a reversible reaction at temperature, T. In this reaction, both H and S were observed to have positive values. If the equilibrium temperature is Te, then the reaction becomes spontaneous at:

1. Te > T
2. T > Te
3. T = Te
4. Te = 5T

Consider the given data : (a) HCl(g) + 10H2O(l) HCl 10H2O; H = -69.01 kJ mol-1 (b) HCl(g) + 40H2O(l) HCl 40H2O; H = -72.79 kJ mol-1 Choose the correct statement :

1. The heat of dilution for the HCl (HCl 10H2O to HCl 40H2O) is 3.78 kJ mol-1.
2. Dissolution of gas in water is an endothermic process.
3. The heat of solution depends on the amount of solvent.
4. The heat of formation of HCl solution is represented by both (a) and (b).

Which of the following properties will change when system containing solution 1 will become solution 2 ? [figure]

1. Molar heat capacity
2. Concentration
3. Gibbs free energy
4. Density

Given below are two statements: In the light of the above statements, choose the correct answer from the options given below

1. Both Statement I and Statement II are false
2. Statement I is true but Statement II is false
3. Both Statement I and Statement II are true
4. Statement I is false but Statement II is true

[figure] Two vessels A and B are connected via stopcock. The vessel A is filled with a gas at a certain pressure. The entire assembly is immersed in water and is allowed to come to thermal equilibrium with water. After opening the stopcock the gas from vessel A expands into vessel B and no change in temperature is observed in the thermometer. Which of the following statement is true ?

1. dq 0
2. The pressure in the vessel B before opening the stopcock is zero
3. dw 0
4. dU 0

Arrange the following in order of magnitude of work done by the system/on the system at constant temperature. (a) | wreversible| for expansion in infinite stages. (b) | wirreversible| for expansion in single stage. (c) | wreversible| for compression in infinite stages. (d) | wirreversible| for compression in single stage. Choose the correct answer from the options given below:

1. d > c = a > b
2. c = a > d > b
3. a > c > b > d
4. a > b > c > d

Which of the following graphs correctly represents the variation of thermodynamic properties of Haber's process?

1. [figure]
2. [figure]
3. [figure]
4. [figure]

500 J of energy is transferred as heat to 0.5 mol of Argon gas at 298 K and 1.00 atm. The final temperature and the change in internal energy respectively are: Given: R = 8.3 J K-1 mol-1

1. 368 K and 500 J
2. 348 K and 300 J
3. 378 K and 300 J
4. 378 K and 500 J

[figure] An ideal gas undergoes a cyclic transformation starting from the point A and coming back to the same point by tracing the path A→B→C→D→A as shown in the three cases above. Choose the correct option regarding U :

1. U(Case-III) > U(Case-II) > U(Case-I)
2. U(Case-I) > U(Case-II) > U(Case-III)
3. U(Case-I) = U(Case-II) = U(Case-III)
4. U(Case-I) > U(Case-III) > U(Case-II)