Thermodynamics Practice Questions - DPP for JEE

 Page 1


PART-I (Single Correct MCQs)
1. In a closed insulated container, a liquid is stirred with a paddle to
increase the temperature, which of the following is true?
(a)
(b)
(c)
(d)
2. The entropy change in the fusion of one mole of a solid melting at
27ºC (Latent heat of fusion, 2930 J mol
–1
) is :
(a) 9.77 J K
–1
 mol
–1
(b) 10.73 J K
–1
 mol
–1
(c) 2930 J K
–1
 mol
–1
(d) 108.5 J K
–1
 mol
–1
Page 2


PART-I (Single Correct MCQs)
1. In a closed insulated container, a liquid is stirred with a paddle to
increase the temperature, which of the following is true?
(a)
(b)
(c)
(d)
2. The entropy change in the fusion of one mole of a solid melting at
27ºC (Latent heat of fusion, 2930 J mol
–1
) is :
(a) 9.77 J K
–1
 mol
–1
(b) 10.73 J K
–1
 mol
–1
(c) 2930 J K
–1
 mol
–1
(d) 108.5 J K
–1
 mol
–1
3. The enthalpy of vapourisation of water from the following two
equations  is.
(a) 6.02 kJ
(b) 40.5 kJ
(c) 62.3 kJ
(d) 1.25 kJ
4. The standard enthalpy of formation of NH
3
 is  – 46.0 kJ mol
–1
. If the
enthalpy of formation of H
2
 from its atoms is– 436 kJ mol
–1
 and that of
N
2
 is – 712 kJ mol
–1
, the average bond enthalpy of N – H bond in NH
3
is
(a) – 964 kJ mol
–1
(b) + 352 kJ mol
–1
(c) + 1056 kJ mol
–1
(d) – 1102 kJ mol
–1
5. Calculate enthalpy change for the change  given that
 ;      
(a) + 512.0 k cal
(b) – 512.0 k cal
(c) 508.0 k cal
(d) – 508.0 k cal
6. On the basis of the following thermochemical data : 
Page 3


PART-I (Single Correct MCQs)
1. In a closed insulated container, a liquid is stirred with a paddle to
increase the temperature, which of the following is true?
(a)
(b)
(c)
(d)
2. The entropy change in the fusion of one mole of a solid melting at
27ºC (Latent heat of fusion, 2930 J mol
–1
) is :
(a) 9.77 J K
–1
 mol
–1
(b) 10.73 J K
–1
 mol
–1
(c) 2930 J K
–1
 mol
–1
(d) 108.5 J K
–1
 mol
–1
3. The enthalpy of vapourisation of water from the following two
equations  is.
(a) 6.02 kJ
(b) 40.5 kJ
(c) 62.3 kJ
(d) 1.25 kJ
4. The standard enthalpy of formation of NH
3
 is  – 46.0 kJ mol
–1
. If the
enthalpy of formation of H
2
 from its atoms is– 436 kJ mol
–1
 and that of
N
2
 is – 712 kJ mol
–1
, the average bond enthalpy of N – H bond in NH
3
is
(a) – 964 kJ mol
–1
(b) + 352 kJ mol
–1
(c) + 1056 kJ mol
–1
(d) – 1102 kJ mol
–1
5. Calculate enthalpy change for the change  given that
 ;      
(a) + 512.0 k cal
(b) – 512.0 k cal
(c) 508.0 k cal
(d) – 508.0 k cal
6. On the basis of the following thermochemical data : 
The value of enthalpy of formation of OH
–
 ion at 25° C is:
(a) –228.88 kJ
(b) +228.88 kJ
(c) –343.52 kJ
(d) –22.88 kJ
7. Consider the following spontaneous reaction
The sign of ?H, ?S, ?G would be respectively
(a) +, –, +
(b) –, + , –
(c) +, +, –
(d) –, –, –
8. The enthalpies of the following reactions are shown below.
H
2
(g) + O
2
(g) ? OH(g) ; ?H = 42.09 kJ mol
–1
H
2
(g) ? 2H(g) ;   ?H = 435.89 kJ mol
–1
O
2
(g) ? 2O(g)  ;    ?H = 495.05 kJ mol
–1
Calculate the O –– H bond energy for the hydroxyl radical.
(a) 223.18 kJ mol
–1
(b) 423.38 kJ mol
–1
(c) 513.28 kJ mol
–1
(d) 113.38 kJ mol
–1
9. 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
Page 4


PART-I (Single Correct MCQs)
1. In a closed insulated container, a liquid is stirred with a paddle to
increase the temperature, which of the following is true?
(a)
(b)
(c)
(d)
2. The entropy change in the fusion of one mole of a solid melting at
27ºC (Latent heat of fusion, 2930 J mol
–1
) is :
(a) 9.77 J K
–1
 mol
–1
(b) 10.73 J K
–1
 mol
–1
(c) 2930 J K
–1
 mol
–1
(d) 108.5 J K
–1
 mol
–1
3. The enthalpy of vapourisation of water from the following two
equations  is.
(a) 6.02 kJ
(b) 40.5 kJ
(c) 62.3 kJ
(d) 1.25 kJ
4. The standard enthalpy of formation of NH
3
 is  – 46.0 kJ mol
–1
. If the
enthalpy of formation of H
2
 from its atoms is– 436 kJ mol
–1
 and that of
N
2
 is – 712 kJ mol
–1
, the average bond enthalpy of N – H bond in NH
3
is
(a) – 964 kJ mol
–1
(b) + 352 kJ mol
–1
(c) + 1056 kJ mol
–1
(d) – 1102 kJ mol
–1
5. Calculate enthalpy change for the change  given that
 ;      
(a) + 512.0 k cal
(b) – 512.0 k cal
(c) 508.0 k cal
(d) – 508.0 k cal
6. On the basis of the following thermochemical data : 
The value of enthalpy of formation of OH
–
 ion at 25° C is:
(a) –228.88 kJ
(b) +228.88 kJ
(c) –343.52 kJ
(d) –22.88 kJ
7. Consider the following spontaneous reaction
The sign of ?H, ?S, ?G would be respectively
(a) +, –, +
(b) –, + , –
(c) +, +, –
(d) –, –, –
8. The enthalpies of the following reactions are shown below.
H
2
(g) + O
2
(g) ? OH(g) ; ?H = 42.09 kJ mol
–1
H
2
(g) ? 2H(g) ;   ?H = 435.89 kJ mol
–1
O
2
(g) ? 2O(g)  ;    ?H = 495.05 kJ mol
–1
Calculate the O –– H bond energy for the hydroxyl radical.
(a) 223.18 kJ mol
–1
(b) 423.38 kJ mol
–1
(c) 513.28 kJ mol
–1
(d) 113.38 kJ mol
–1
9. 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
(a) –315 kJ
(b) +315kJ
(c) –630 kJ
(d) –3.15 kJ
10. Using the data provided, calculate the multiple bond energy (kJ mol
–1
)
of a C C bond in C
2
H
2
. That energy is (take the bond energy of a C –
H bond as 350 kJ mol
–1
)
2C(s) + H
2
(g) HC = CH(g);     ?H = 225 kJ mol
–1
2C(s) 2C(g) ; ?H = 1410 kJ mol
–1
H
2
(g) 2H(g) ; ?H = 330 kJ mol
–1       
(a) 1165
(b) 837
(c) 865
(d) 815
11. For a given reaction, ?H = 35.5 kJ mol
-1
  and ?S = 83.6 JK
-1 
mol
-1
. The
reaction is spontaneous at : (Assume that ?H and ?S do not vary with
tempearature)
(a) T > 425 K
(b) All temperatures
(c) T > 298 K
(d) T < 425 K
12. If an endothermic reaction is non-spontaneous at freezing point of water
and becomes feasible at its boiling point, then
(a) is –ve,  is +ve
(b) and  both are +ve
(c) and  both are –ve
Page 5


PART-I (Single Correct MCQs)
1. In a closed insulated container, a liquid is stirred with a paddle to
increase the temperature, which of the following is true?
(a)
(b)
(c)
(d)
2. The entropy change in the fusion of one mole of a solid melting at
27ºC (Latent heat of fusion, 2930 J mol
–1
) is :
(a) 9.77 J K
–1
 mol
–1
(b) 10.73 J K
–1
 mol
–1
(c) 2930 J K
–1
 mol
–1
(d) 108.5 J K
–1
 mol
–1
3. The enthalpy of vapourisation of water from the following two
equations  is.
(a) 6.02 kJ
(b) 40.5 kJ
(c) 62.3 kJ
(d) 1.25 kJ
4. The standard enthalpy of formation of NH
3
 is  – 46.0 kJ mol
–1
. If the
enthalpy of formation of H
2
 from its atoms is– 436 kJ mol
–1
 and that of
N
2
 is – 712 kJ mol
–1
, the average bond enthalpy of N – H bond in NH
3
is
(a) – 964 kJ mol
–1
(b) + 352 kJ mol
–1
(c) + 1056 kJ mol
–1
(d) – 1102 kJ mol
–1
5. Calculate enthalpy change for the change  given that
 ;      
(a) + 512.0 k cal
(b) – 512.0 k cal
(c) 508.0 k cal
(d) – 508.0 k cal
6. On the basis of the following thermochemical data : 
The value of enthalpy of formation of OH
–
 ion at 25° C is:
(a) –228.88 kJ
(b) +228.88 kJ
(c) –343.52 kJ
(d) –22.88 kJ
7. Consider the following spontaneous reaction
The sign of ?H, ?S, ?G would be respectively
(a) +, –, +
(b) –, + , –
(c) +, +, –
(d) –, –, –
8. The enthalpies of the following reactions are shown below.
H
2
(g) + O
2
(g) ? OH(g) ; ?H = 42.09 kJ mol
–1
H
2
(g) ? 2H(g) ;   ?H = 435.89 kJ mol
–1
O
2
(g) ? 2O(g)  ;    ?H = 495.05 kJ mol
–1
Calculate the O –– H bond energy for the hydroxyl radical.
(a) 223.18 kJ mol
–1
(b) 423.38 kJ mol
–1
(c) 513.28 kJ mol
–1
(d) 113.38 kJ mol
–1
9. 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
(a) –315 kJ
(b) +315kJ
(c) –630 kJ
(d) –3.15 kJ
10. Using the data provided, calculate the multiple bond energy (kJ mol
–1
)
of a C C bond in C
2
H
2
. That energy is (take the bond energy of a C –
H bond as 350 kJ mol
–1
)
2C(s) + H
2
(g) HC = CH(g);     ?H = 225 kJ mol
–1
2C(s) 2C(g) ; ?H = 1410 kJ mol
–1
H
2
(g) 2H(g) ; ?H = 330 kJ mol
–1       
(a) 1165
(b) 837
(c) 865
(d) 815
11. For a given reaction, ?H = 35.5 kJ mol
-1
  and ?S = 83.6 JK
-1 
mol
-1
. The
reaction is spontaneous at : (Assume that ?H and ?S do not vary with
tempearature)
(a) T > 425 K
(b) All temperatures
(c) T > 298 K
(d) T < 425 K
12. If an endothermic reaction is non-spontaneous at freezing point of water
and becomes feasible at its boiling point, then
(a) is –ve,  is +ve
(b) and  both are +ve
(c) and  both are –ve
(d) is +ve,  is -ve
13. The standard enthalpies of formation of CO
2
(g), H
2
O(l) and glucose(s)
at 25°C are –400 kJ/mol, –300 kJ/mol and –1300 kJ/mol, respectively.
The standard enthalpy of combustion per gram of glucose at 25°C is
(a) +2900 kJ
(b) –2900 kJ
(c) –16.11 kJ
(d) +16.11 kJ
14. If at 298 K the bond energies of C — H, C — C, C = C and H — H
bonds are respectively 414, 347, 615 and 435 kJ mol
–1
, the value of
enthalpy change for the reaction
at  298 K will be
(a) – 250 kJ
(b) + 125 kJ
(c) – 125 kJ
(d) + 250 kJ
15. Standard entropy of X
2
, Y
2
 and X Y
3
 are 60, 40 and50 J K
–1
 mol
–1
,
respectively. For the reaction,
, to be at equilibrium, the
temperature will be
(a) 1250 K
(b) 500 K
(c) 750 K
(d) 1000 K
16. Bond enthalpies of ,  and HX are in the ratio 2 : 1 : 2. If