${H}_{2}\left(g\right)+\frac{1}{2}{O}_{2}\left(g\right)\to {H}_{2}O\left(l\right)$

B.E. (H-H) = x1; B.E. (O=O) = x2 B.E. (O-H) = x3

Latent heat of vaporization of water liquid into water vapour = x4, then $∆{H}_{f}$(heat of formation of liquid water) is-

1. ${x}_{1}+\frac{{x}_{2}}{2}-{x}_{3}+{x}_{4}$

2. $2{x}_{3}-{x}_{1}-\frac{{x}_{2}}{2}-{x}_{4}$

3. ${x}_{1}+\frac{{x}_{2}}{2}-2{x}_{3}-{x}_{4}$

4. ${x}_{1}+\frac{{x}_{2}}{2}-2{x}_{3}+{x}_{4}$

Concept Questions :-

Enthalpy and It's Type
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Difficulty Level:

In a process the pressure of a gas is inversely proportional to the square of the volume. If temperature of the gas is increases, then work done on the gas-

1. is positive

2. is negative

3. is zero

4. may be positive

Concept Questions :-

Thermodynamics' Properties and process
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Difficulty Level:

The enthalpies of formation of CO2(g) and CO(g) at 298 K are in the ratio 2.57 : 1. For the reaction,

1. -150.6 kJ mol-1

2. -109.8 kJ mol-1

3. -130.2 kJ mol-1

4. -141.8 kJ mol-1

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Difficulty Level:

In an adiabatic expansion the product of pressure and volume-

1. decreases

2. increases

3. remains constant

4. first increase then decreases

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Difficulty Level:

The molar entropy of vapourisation of acetic acid is 144.4 cal K-1 mol-1 at its boiling point ${118}^{\circ }C$. The latent heat of vapourisation of acetic acid is

1. 49 cal g-1

2. 64 cal g-1

3. 94 cal g-1

4. 84 cal g-1

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Difficulty Level:

100 ml of 0.3 M HCl solution is mixed with 100 ml of 0.35 M NaOH solution. The amount of heat liberated is

1. 7.3 kJ

2. 5.71 kJ

3. 10.42 kJ

4. 1.713 kJ

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Difficulty Level:

Five moles of ideal gas expand isothermally and reversibly from an initial pressure of 100 atm to a final pressure of 1 atm at ${27}^{\circ }C$. The work done by the gas is

1. 3455 cal

2. 6909 cal

3. 0

4. 69010 cal

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Difficulty Level:

The quantity ${\delta }_{q}$ i.e. heat absorbed an infinitesimal process is

1. Dependent on the path of transformation

2. Dependent on the thermodynamic state of the system

3. Independent of both

4. An exact differential

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Difficulty Level:

An ideal gas absorbs 2000 cals of heat from a heat reservoir and does mechanical work equivalent 4200 J. The change in internal energy of the gas is

1. 3000 cals

2. 2000 cals

3. 1500 cals

4. 1000 cals

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Difficulty Level:

For an ideal gas four processes are marked as 1, 2, 3 and 4 on P-V diagram as shown in figure. The amount of heat supplied to the gas in the process 1, 2, 3 and 4 are Q1, Q2, Q3 and Q4 repectively, then correct order of heat supplied to the gas is

[AB is process-1, AC is process-2, AD is adiabatic process-3 and AE is process-4]

1. ${Q}_{1}>{Q}_{2}>{Q}_{3}>{Q}_{4}$

2. ${Q}_{1}>{Q}_{2}>{Q}_{4}>{Q}_{3}$

3.  ${Q}_{1}>{Q}_{4}>{Q}_{2}>{Q}_{4}$

4. ${Q}_{1}<{Q}_{2}<{Q}_{3}<{Q}_{4}$