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NEET Chemistry : Thermodynamics

Multiple Choice Questions

21.

Consider the change in oxidation state of Bromine corresponding to different emf values as shown in the diagram below :

$B r O_{4}^{-} \overset{1.82}{\to} B r O_{3}^{-} \overset{1.5 V}{\to} H B r O \overset{1.595}{\to} B r_{2} \overset{1.0652 V}{\to} B r^{-}$

Then the species undergoing disproportionation is

$B r O_{3}^{-}$
$B r O_{4}^{-}$
HBrO
Br₂

22.

Assume each reaction is carried out in an open container. For which reaction will ΔH = ΔE?

H₂ (g) + Br₂ (g) →2HBr (g)
C (s) + 2 H₂O (g) → 2 H₂ (g) + CO₂ (g)
PCl₅ (g) →PCl₃ (g) + Cl₂ (g)
PCl₅ (g) →PCl₃ (g) + Cl₂ (g)

23.

The correction factor ‘a’ to the ideal gas equation corresponds to

Density of the gas molecules
Volume of the gas molecules
Forces of attraction between the gas molecules
Electric field present between the gas molecules

24.

The bond dissociation energies of X₂, Y₂ and XY are in the ratio of 1 : 0.5: 1. ΔH for the formation of XY is –200 kJ mol–1. The bond dissociation energy of X₂ will be

200 kJ mol^-1
100 kJ mol^-1
400 kJ mol^-1
800 kJ mol^-1

25.

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 internal energy ΔU of the gas in joules will be

1136.5 J
-500 J
-505 J
-505 J

26.

The enthalpy of combustion of H₂, cyclohexene (C₆H₁₀) and cyclohexene (C₆H₁₂) are -241, -3800 and -3920 kJ per mol respectively.The heat of hydrogenation of cyclohexane is:

-212 kJ mol
+121 kJ mol
+242 kJ per mol
+242 kJ per mol

27.

Consider the following reactions:

$straight i right parenthesis space straight H to the power of plus space left parenthesis straight g right parenthesis thin space space plus space OH to the power of minus space left parenthesis aq right parenthesis space equals space straight H subscript 2 straight O space left parenthesis straight l right parenthesis space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space increment straight H space equals space minus space straight x subscript 1 space kJ space mol to the power of blank to the power of negative 1 end exponent end exponent ii right parenthesis space straight H subscript 2 space left parenthesis straight g right parenthesis thin space space plus space straight O subscript 2 space left parenthesis straight q right parenthesis space equals space straight H subscript 2 straight O space left parenthesis straight l right parenthesis space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space increment straight H space equals space minus space straight x subscript 2 space kJ space mol to the power of blank to the power of negative 1 end exponent end exponent iii right parenthesis space CO subscript 2 space left parenthesis straight g right parenthesis thin space space plus space straight H subscript 2 space left parenthesis straight g right parenthesis space equals space straight H subscript 2 straight O space left parenthesis straight l right parenthesis space plus space CO subscript 2 space left parenthesis straight g right parenthesis space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space increment straight H space equals space minus space straight x subscript 3 space kJ space mol to the power of blank to the power of negative 1 end exponent end exponent iv right parenthesis straight C subscript 2 straight H subscript 2 space left parenthesis straight g right parenthesis thin space space plus 5 over 2 space straight O subscript 2 space left parenthesis straight g right parenthesis space equals space straight H subscript 2 straight O space left parenthesis straight l right parenthesis space plus 2 CO subscript 2 space left parenthesis straight g right parenthesis space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space increment straight H space equals space plus space straight x subscript 4 space kJ space mol to the power of blank to the power of negative 1 end exponent end exponent$
Enthalpy of formation of H₂O (l) is:

- x₂ kJ mol^-1
+ x₃ kJ mol^-1
- x₄ kJ mol^-1
- x₄ kJ mol^-1

28.

Which one of the following conditions will favour maximum formation of the product in the reaction,

$A_{2} (g) + B_{2} (g) \overset{}{⇋} X_{2} (g) ∆_{r} H = - X k J ?$

Low temperature and high pressure
Low temperature and low pressure
High temperature and low pressure
High temperature and high pressure

29.

Given that bond energy of H-H and Cl- Cl are 430 kJ mol^-1 and 240 kJ mol^-1 respectively and ΔH_f for HCl is -90 kJ mol^-1. Bond and ΔH_f for HCl is -90 kJ mol^-1.Bond enthalpy of HCl is:

290 kJ mol^-1
380 kJ mol^-1
425 kJ mol^-1
425 kJ mol^-1

30.

For a given reaction, ΔH = 35.5 kJ mol^–1 and ΔS = 83.6 JK^–1 mol^–1. The reaction is spontaneous at (Assume that ΔH and ΔS do not vary with temperature)

T < 425 K
T > 425 K
All temperatures
All temperatures

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NEET Chemistry : Thermodynamics

Multiple Choice Questions