The correct statement among the following is-

  • The presence of reacting species in a covered beaker is an example of an open system.

  • There is an exchange of energy as well as matter between the system and the surroundings in a closed system.

  • The presence of reactants in a closed vessel made up of copper is an example of a closed system.

  • The presence of reactants in a thermos flask or any other closed insulated vessel is an example of a closed system.

If the volume of a gas is reduced to half from its original volume, then the specific heat will-

  •   Reduce to half

  •   Be Doubled

  •   Remain constant

  •   Increase four times

fU of formation of CH4(g) at certain temperature is -393 kJ mol-1. The value of fH is-

  • Zero

  •  <fU

  •  >fU

  • Equal to fU

In an adiabatic process, no transfer of heat takes place between the system and its surroundings. The correct option for free expansion of an ideal gas under adiabatic condition from the following is -

  •  q=0, T0, W=0

  •  q0, T=0, W=0

  •  q=0, T=0, W=0

  •  q=0, T=0, W0

The pressure-volume work for an ideal gas can be calculated by using the expression W=ViVfpexdV. The work can also be calculated from the pV-plot by using the area under the curve within the specified limits. An ideal gas is compressed (a) reversibly or (b) irreversibly from volume Vi to Vf. The correct option is -

  •   W (reversible)=W (irreversible)

  •   W (reversible)<W(irreversible)

  •   W (reversible)=W (irreversible)

  •   W (reversible)=W (irreversible)+pex.V

The entropy change can be calculated by using the expression S=qrevT. When water freezes in a glass beaker, the correct statement among the following is -

  •  S (system) decreases but S (surroundings) remains the same

  •  S (system) increases but S (surroundings) decreases

  •  S (system) decreases but S (surroundings) increases

  •  S (system) decreases but S (surroundings) also decreases

Consider the reactions given below. On the basis of these reactions find out which of the

the algebraic relationships is correct?

(i) C(g) +4H (g) CH4(g); Hr =x kJ mol-1(ii) C(graphite) + 2H2 (g)   CH4; Hr  = y kJ mol-1

  •   x=y

  •   x=2y

  •   x>y

  •   x<y

The enthalpies of elements in their standard states are taken as zero. The enthalpy of formation of a compound is -

  • Generally negative

  • Always positive

  • Zero

  • Never negative

Consider the following statement:

"A thermodynamic quantity is a state function"

The correct option is-

 
  • Used to determine heat changes

  • Whose value is independent of the path

  • Used to determine pressure-volume work

  • Whose value depends on temperature only.

A necessary condition for an adiabatic change is-

  • ∆T = 0

  • ∆P = 0

  • q = 0

  • w = 0

The enthalpy of formation of all elements in their standard state is-

  • Unity

  • Zero

  • Less than zero

  • Different for each element

U° for combustion of methane is -x kJ mol-1.

The value of H° for the same reaction would be -

1. = U°2. > U°3. < U°4. =0

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701 J of heat is absorbed by a system and 394 J of work is done by the system.

The change in internal energy for the process is-

1. 307 J2. -307 J3. 1095 J4. -701 J

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The reaction of cyanamide, NH2CN (s) with dioxygen, was carried out in a bomb calorimeter, and ∆U was found to be -742.7 kJ mol-1 at 298 K.

NH2CN (s) + 32O2(g)  N2 (g) + CO2(g) + H2O (l)

The enthalpy change for the reaction at 298 K would be -

1. -741.3 kJ mol-12. + 753.9 kJ mol-13. + 772. 7 kJ mol-14. -845. 1 kJ mol-1

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The amount of heat needed to raise the temperature of 60.0 g of aluminum from 35°C to 55°C would be -

(Molar heat capacity of Al is 24 J mol-1 K-1)

1. 1.07 J2. 1.07 kJ3. 106.7 kJ4. 100.7 kJ

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The enthalpy of formation of COg, CO2g, N2Og , and N2O4g are

–110 kJ mol-1, – 393 kJ mol-1, 81 kJ mol-1, and 9.7 kJ mol-1 respectively.

The value of rH for the reaction would be-

N2O4g+3COgN2Og+3CO2g

1. -777.7 kJ mol-12.  +777.7 kJ mol-13.  +824.9 kJ mol-14. - 345.4 kJ mol-1

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 N2 + 3 H2  2NH3 ; rH° = -92.4 kJ mol-1

The standard enthalpy of formation of NH3 gas in the above reaction would be-

1. -92.4  J mol-12.  -46.2 kJ mol-13.  + 46.2 J mol-14. + 92.4 kJ mol-1

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The standard enthalpy of formation of CH3OH(l) from the following data is -

CH3OHl+ 32O2g  CO2g + 2H2Ol; rH° = -726 kJ mol-1C(s) + O2g  CO2g ; cH° = -393 kJ mol-1H2g + 12O2g  H2Ol ; fH° = -286 kJ mol-1

1. -239 kJ mol-12. + 239 kJ mol-13. -47 kJ mol-14. +47 kJ mol-1

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vapH° (CCl4) = 30.5 kJ mol-1fH° (CCl4) = - 135.5 kJ mol-1aH° (C) = 715.0 kJ mol-1aH° (Cl2)= 242 kJ mol-1

The enthalpy change for the reaction

 CCl4 (g)  C(g) + 4Cl (g) would be -

1. 326 kJ mol-12. 1304 kJ mol-13. -328 kJ mol-14. -1304 kJ mol-1

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For an isolated system with ∆U = 0, the ∆S value will be-

  • Positive

  • Negative

  • Zero

  • Not possible to define

For the reaction at 298 K,

2A + B → C

H = 400 kJ mol-1 and S = 0.2 kJ K-1 mol-1 .Reaction will become spontaneous at-

1. 1500 K2. 2000 K3. 100 K4. 1900K

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For the reaction 2A (g) + B(g)  2D (g); U° = -10.5 kJ and S° = -44.1 J K-1 , the value of G° for the given reaction would be-

  • 1.6 J

  • - 0.16 KJ

  • 0.16 KJ

  • 1.6 KJ

The equilibrium constant for a reaction is 10. The value of G° will be-

(R = 8.314 J K-1 mol-1 ; T = 300 K)

1. -5.74 kJ mol-12. - 5.74 J mol-13. + 4.57 kJ mol-14. -57.4 kJ mol-1

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Entropy change in surroundings when 1.00 mol of H2Ol is formed under standard conditions. fHθ=-286 kJ mol-1 is

1. -959.73 J K-1 mol-12. 234.98 J K-1 mol-13. 959.73 J K-1 mol-14. 312.56 J K-1 mol-1

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If for a certain reaction rH is 30 kJ mol–1 at 450 K,the value of rS (in JK–1 mol–1) for which the same reaction will be spontaneous at the same temperature is

  • 70

  • –33

  • 33

  • -70

Consider the following processes :

                                       ∆H (kJ/mol)
½ A → B                            + 150
3B → 2C + D                      –125
E + A → 2D                        +350

For B + D → E + 2C, ∆H will be-

  • 325 kJ/mol 

  • 525 kJ/mol

  • –175 kJ.mol 

  • –325 kJ/mol

For vaporization of water at 1 atmospheric pressure, the values of ∆H and ∆S are 40.63 kJ mol–1 and 108.8 JK–1 mol–1, respectively. The temperature when Gibbs energy change (∆G) for this transformation will be zero, is -

  • 393.4 K

  • 373.4 K

  • 293.4 K

  • 273.4 K

Three moles of an ideal gas expanded spontaneously into vaccum. The work done will be

  • 3 Joules

  • 9 Joules

  • Zero

  • Infinite

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