CBSE Class 11 Chemistry Thermodynamics MCQs Set C

Question: For the reaction, 2Cl_(g) → Cl_2(g), the correct option is
a) ΔrH > 0 and ΔrS > 0
b) ΔrH > 0 and ΔrS < 0
c) ΔrH < 0 and ΔrS > 0
d) ΔrH < 0 and ΔrS < 0
Answer: d

Question: Considering the reaction,C(s) + O₂ (g) → CO₂ (g)+393.5 kJ the signs of ΔH , ΔS and AG respectively are
a) +, - , -
b) -, +, +
c) - , - , -
d) - ,+, -
Answer: d

Question: In a fuel cell methanol is used as fuel and oxygen gas is used as an oxidiser. The reaction is
CH₃OH(/) + 3/2 O₂(g) ➔ CO₂ (g)+2H₂ O(/).
At 298 K standard Gibb's energies of fo1mation for CH₃OH(/), H₂O(/) and CO₂ (g) are-166.2, -237.2 and -394.4 kJ mol^-1 respectively. If standard enthalpy of combustion of methanol is -726kJ mol^-1 , efficiency of the fuel cell will be 
a) 80%
b) 87%
c) 90%
d) 97%
Answer: d 

Question: Which of the following is an intensive property? 
a) Temperature
b) Viscosity
c) Surface tension
d) All of these
Answer: d

Question: For the process H₂O(/) → H₂O(g) at T = 1000° Cand 1 atmosphere pressure, the con-ect choice is 
a) ΔS_system > 0 and ΔS_system > 0
b) ΔS_system > 0 and ΔS_system < 0
c) ΔS_system < 0 and ΔS_system > 0
d) ΔS_system < 0 and ΔS_system < 0
Answer: b

Question: Standard enthalpy of vaporisation DvapH° for water at 100°C is 40.66 kJ mol^–1. The internal energy of vaporisation of water at 100°C (in kJ mol^–1) is
a) +37.56
b) – 43.76
c) + 43.76
d) + 40.66
(Assume water vapour to behave like an ideal gas)
Answer: a

Question: For the reaction, C₃H_8(g) + 5O_2(g) → 3CO_2(g) + 4H₂O_(l) at constant temperature, ΔH – ΔE is
a) + RT
b) –3RT
c) +3RT
d) –RT
Answer: b

Question: When 0. 2 g of 1-butanol was burnt in a suitable apparatus, the heat evolved was sufficient to raise the temperature of 200 g water by 5°C. The enthalpy of combustion of 1-butanol in kcal mol-1 will be 
a) + 37
b) + 370
c) –370
d) –740
Answer: c

Question: Heat of combustion ΔH for C_(s), H_2(g) and CH_4(g) are –94, –68 and –213 kcal/mol, then ΔH for C_(s) + 2H_2(g) → CH_4(g) is
a) –17 kcal
b) –111 kcal
c) –170 kcal
d) –85 kcal
Answer: a

Question: Which of the following taking place in the blast furnace is endothennic ? 
a) CaCO₃ → CaO+ CO₂
b) 2C+ O₂ → 2CO
c) C + O₂ → CO₂
d) Fe₂O₃ + 3CO → 2Fe + 3CO₂
Answer: a

Question: Considering entropy (S) as a thermodynamic parameter, the criterion for the spontaneity of any process is
a) ΔS_system + ΔS_surroundings > 0
b) ΔS_system – ΔS_surroundings > 0
c) ΔS_system > 0 only
d) ΔS_surroundings > 0 only. 
Answer: a

Question: Which of the following is a path fonction? 
a) Internal energy
b) Enthalpy
c) Work
d) Entropy
Answer: d

Question: If enthalpies of formation for C2H_4(g), CO_2(g) and H₂O_(l) at 25°C and 1 atm pressure are 52, – 394 and – 286 kJ/mol respectively, then enthalpy of combustion of C₂H_4(g) will be
a) + 141.2 kJ/mol 
b) + 1412 kJ/mol
c) – 141.2 kJ/mol
d) – 1412 kJ/mol
Answer: d

Question: For the reaction, C₂H₅OH_(l) + 3O_2(g) → 2CO_2(g) + 3H₂O_(l) which one is true?
a) ΔH = ΔE – RT
b) ΔH = ΔE + RT
c) ΔH = ΔE + 2RT
d) ΔH = ΔE – 2RT 
Answer: a

Question: Given that bond energies of H – H and Cl – Cl are 430 kJ mol–1 and 240 kJ mol^–1 respectively and DHf for HCl is –90 kJ mol–1, bond enthalpy of HCl is
a) 380 kJ mol^–1
b) 425 kJ mol^–1
c) 245 kJ mol^–1
d) 290 kJ mol^–1
Answer: b

Question: A gas is allowed to expand in a well insulated container against a constant external pressure of 2.5 atm from an initial volume of 2.50 L to a final volume of 4.50 L. The change in nternal energy DU of the gas in joules will be
a) –500 J
b) –505 J
c) +505 J
d) 1136.25 J
Answer: b

Question: The molar heat capacity of water at constant pressure, C , is 75 J K^–1 mol^–1. When 1.0 kJ of heat is supplied to 100 g of water which is free to expand, the increase in temperature f water is
a) 1.2 K
b) 2.4 K
c) 4.8 K
d) 6.6 K 
Answer: b

Question: The absolute enthalpy of neutralisation of the reaction : MgO_(s) + 2HCl_(aq) → MgCl_2(aq) + H2O_(l) will be
a) –57.33 kJ mol^–1
b) greater than –57.33 kJ mol^–1
c) less than –57.33 kJ mol^–1
d) 57.33 kJ mol^–1
Answer: c 

Question: In equilibrium state the value of AG is
a) zero
b) negative
c) positive
d) may be negative or positive
Answer: a 

Question: Which of the following is the correct equation?
a) ΔU = ΔW + DQ
b) ΔU = ΔQ – W
c) ΔW = ΔU + ΔQ
d) None of the options
Answer: b

Question: The work done during the expansion of a gas from a volume of 4 dm3 to 6 dm3 against a constant external pressure of 3 atm is (1 L atm = 101.32 J)
a) – 6 J
b) – 608 J
c) + 304 J
d) – 304 J 
Answer: b

Question: The latent heat of fusion of ice at 0° C is 80 cal/g. Entropy change (ΔS) accompanying the melting of 1 g of ice at 0° C would be (units cal/g/K) 
a) 273
b) 8.0
c) 0.9
d) 0.293 
Answer: d

Question: For the reaction, X₂O_4(l) 2XO_2(g) DU = 2.1 kcal, ΔS = 20 cal K^–1 at 300 K Hence, ΔG is
a) 2.7 kcal
b) – 2.7 kcal
c) 9.3 kcal
d) – 9.3 kcal
Answer: b

Question: In which reaction there will be increase in entropy? 
a) Na(s) + H₂O(l) → NaOH(/)+ 1/2H₂ (g)
b) Ag⁺ (aq) + Cl^- (aq) → AgCl(s)
c) H₂ (g) + 1/2 O₂ (g) → H₂0(/)
d) Cu²⁺ (aq) + 4NH₃ (g) → [Cu(NH₃)₄]²⁺ (aq) 
Answer: a

Question: I₂ (s) ⇌ 12 (g); ΔH = + 40 kcal, ΔS = 80 cal. The sublimation point of I₂ (s) will be 
a) 100°C
b) 127°C
c) 227°C
d) 500°C
Answer: c 

Question: The values of ΔH and ΔS for the reaction, C_(graphite) + CO_2(g) → 2CO_(g) are 170 kJ and 170 J K^–1, respectively. This reaction will be spontaneous at
a) 910 K
b) 1110 K
c) 510 K
d) 710 K
Answer: b

Question: Enthalpy of CH4 + 1/2 O₂ → CH₃OH is negative. If enthalpy of combustion of CH₄ and CH₃OH are x and y respectively, then which relation is correct?
a) x > y
b) x < y
c) x = y
d) x ≥ y
Answer: a

Question: The enthalpy of fusion of water is 1.435 kcal/mol. The molar entropy change for the melting of ice at 0°C is
a) 10.52 cal/(mol K)
b) 21.04 cal/(mol K)
c) 5.260 cal/(mol K)
d) 0.526 cal/(mol K)
Answer: c

Question: For an ideal binary liquid mixture 
a) ΔS (mix) = 0; ΔG (mix) = 0
b) ΔH (mix) = 0; ΔS (mix) < 0
c) ΔV (mix) = 0; ΔG (mix) > 0
d) ΔS (mix) > 0; ΔG (mix) < 0
Answer: d

Question: C₂H₂ + 5/2 O₂ → 2CO₂ + H₂O ; ΔH = –310 kcal 
C+O₂ → CO2; ΔH = –94 kcal 
H2 + 1/2 O₂ → H2O; ΔH = –68 kcal
On the basis of the above equations, ΔH_f (enthalpy of fom1ation) of C₂H₂ will be 
a) –148 kcal
b) + 54 kcal
c) –54 kcal
d) + 80 kcal
Answer: b

Question: Identify the correct statement for change of Gibbs’ energy for a system (ΔG_system) at constant temperature and pressure.
a) If ΔG_system < 0, the process is not spontaneous.
b) If ΔG_system > 0, the process is spontaneous.
c) If ΔG_system = 0, the system has attained equilibrium.
d) If ΔG_system = 0, the system is still moving in a particular direction.
Answer: c

Question: Change in enthalpy for reaction, 2H₂O_2(l) → 2H₂O_(l) + O_2(g) if heat of formation of H₂O_2(l) and H₂O_(l) are –188 and –286 kJ/mol respectively, is
a) –196 kJ/mol
b) +196 kJ/mol
c) +948 kJ/mol
d) –948 kJ/mole 
Answer: a

Question: What is the entropy change (in J K^–1 mol^–1) when one mole of ice is converted into water at 0°C? (The enthalpy change for the conversion of ice to liquid water is 6.0 kJ mol^–1 at °C.)
a) 20.13
b) 2.013
c) 2.198
d) 21.98
Answer: d 

 Question: Which of the following are not state functions?
(I) q + w (II) q
(III) w (IV) H – TS
a) (I), (II) and (III)
b) (II) and (III)
c) (I) and (IV)
d) (II), (III) and (IV)
Answer: b