RACE # 45 THER MODYNAM ICS AND THERMOCHEMISTRY C HE M I S T R Y
FLOT
1. What is the difference between change in enthalpy and change in internal energy at constant volume :
(A) 0 (B) VdP (C) –VdP (D) PdV
2. The work done in an adiabatic process on an ideal gas by a constant external pressure would be :
(A) Zero (B) DE (C) DH (D) q
3. Which of the following is correct option for free expansion of an ideal gas under adiabatic condition ?
(A) q = 0, DT ¹ 0, w = 0 (B) q ¹ 0, DT = 0, w = 0
(C) q = 0, DT = 0, w = 0 (D) q = 0, DT < 0, w ¹ 0
4. Consider the cyclic process R ® S ® R as shown in the fig. You are told that one of the path is adiabatic and
the other one isothermal. Which one of the following is(are) true?
(A) Process R ® S is isothermal
(B) Process S ® R is adiabatic
(C) Process R ® S is adiabatic
(D) Such a graph is not possible
5. Calculate the heat needed to raise the temperature of 20 g iron from 25ºC to 500ºC, if specific heat capacity of
iron is 0.45 JK–1 g–1 .
(A) 4275 J (B) 225 J (C) 15.66 J (D) 2250 J
6. The ratio of slopes of P–V plots for reversible adiabatic process and reversible isothermal process of an ideal
gas is equal to :
(A) g (B) 1 – g (C) (g – 1) (D) 1/g
7. For an ideal gas having molar mass M, specific heat at constant pressure can be given as :
g RM R RM gR
(A) g –1
(B) M( g - 1)
(C) g –1
(D) M( g - 1)
8. P–V plots for two gases during an adiabatic process are given in the figure :
Volume
Plot A and plot B should correspond to : (Assume ideal behaviour)
(A) He and O2 (B) SO2 and Ar (C) O2 and He (D) Both (B) and (C)
9. An ideal gas with Cv = 3R expands adiabatically into a vacuum thus doubling its volume. The final temperatue
is given by :
(A) T2 = T1[2–1/3] (B) T2 = T1 (C) T2 = 2T1 (D) T2 = T1
2
3
10. A monoatomic ideal gas (CV = R) is allowed to expand adiabatically and reversibly from initial volume of 8
2
L at 300 K to a volume of V2 at 250 K. V2 is : (Given (4.8)1/2 = 2.2)
(A) 10.56 L (B) 17.6 L
(C) 11.52 L (D) Expansion not possible since temperature has decreased
FLOT
1. What is the difference between change in enthalpy and change in internal energy at constant volume :
(A) 0 (B) VdP (C) –VdP (D) PdV
2. The work done in an adiabatic process on an ideal gas by a constant external pressure would be :
(A) Zero (B) DE (C) DH (D) q
3. Which of the following is correct option for free expansion of an ideal gas under adiabatic condition ?
(A) q = 0, DT ¹ 0, w = 0 (B) q ¹ 0, DT = 0, w = 0
(C) q = 0, DT = 0, w = 0 (D) q = 0, DT < 0, w ¹ 0
4. Consider the cyclic process R ® S ® R as shown in the fig. You are told that one of the path is adiabatic and
the other one isothermal. Which one of the following is(are) true?
(A) Process R ® S is isothermal
(B) Process S ® R is adiabatic
(C) Process R ® S is adiabatic
(D) Such a graph is not possible
5. Calculate the heat needed to raise the temperature of 20 g iron from 25ºC to 500ºC, if specific heat capacity of
iron is 0.45 JK–1 g–1 .
(A) 4275 J (B) 225 J (C) 15.66 J (D) 2250 J
6. The ratio of slopes of P–V plots for reversible adiabatic process and reversible isothermal process of an ideal
gas is equal to :
(A) g (B) 1 – g (C) (g – 1) (D) 1/g
7. For an ideal gas having molar mass M, specific heat at constant pressure can be given as :
g RM R RM gR
(A) g –1
(B) M( g - 1)
(C) g –1
(D) M( g - 1)
8. P–V plots for two gases during an adiabatic process are given in the figure :
Volume
Plot A and plot B should correspond to : (Assume ideal behaviour)
(A) He and O2 (B) SO2 and Ar (C) O2 and He (D) Both (B) and (C)
9. An ideal gas with Cv = 3R expands adiabatically into a vacuum thus doubling its volume. The final temperatue
is given by :
(A) T2 = T1[2–1/3] (B) T2 = T1 (C) T2 = 2T1 (D) T2 = T1
2
3
10. A monoatomic ideal gas (CV = R) is allowed to expand adiabatically and reversibly from initial volume of 8
2
L at 300 K to a volume of V2 at 250 K. V2 is : (Given (4.8)1/2 = 2.2)
(A) 10.56 L (B) 17.6 L
(C) 11.52 L (D) Expansion not possible since temperature has decreased
