# What is the entropy change for the reaction given below,  2H2 (g) + O2 (g) $\to$2H2O(l) at temperature 300 K? Standard entropies of H2 (g), O2(g) and H2O(l) are 126.6, 201.20 and 68.0 JK-1mol-1 respectively. 1. -318.4 JK-1mol-1                           . 2. 318.4 JK-1mol-1  3. 31.84 JK-1mol-1                              4. none of these

Subtopic:  Spontaneity & Entropy |
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If S$°$ for H2, Cl2 and HCl are 0.13, 0.22 and 0.19 kJ K-1mol-1 respectively. The total change in standard entropy for the reaction, H2 + Cl2 $\to$2HCl is:

1. 30 J K-1mol-1

2. 40 J K-1mol-1

3. 60 J K-1mol-1

4. 20 J K-1mol-1

Subtopic:  Spontaneity & Entropy |
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The direct conversion of A to B is difficult and thus it is converted by path A$\to$C$\to$D$\to$B. Given

(Where e.u. is the entropy unit)
then $∆{\mathrm{S}}_{\mathrm{A}\to \mathrm{B}}$ would be:

1. +60 e.u

2. +100 e.u

3. -60 e.u

4. -100 e.u

Subtopic:  Hess's Law |
60%
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In a flask, colourless N2O4(g) is in equilibrium with brown coloured NO2(g). At equilibrium when the flask is heated to 100$°$C, the brown colour deepens and on cooling it becomes less coloured. Which statement is incorrect about this observation?

1. The $∆$H for the reaction N2O4(g)$⇌$ 2NO2(g) is +ve

2. Paramagnetism increases on heating

3. The $∆$H-$∆$U at 100$°$C is equal to 200 cal

4. Dimerisation is reduced on heating

Subtopic:  First Law of Thermodynamics |
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Enthalpy of the reaction,

CH4(g) + 1/2O2(g) CH3OH(l), is negative. If the enthalpy of combustion of CH4 and CH3OH are x and y respectively, then
which relation is correct?

1. x>y

2. x<y

3. x=y

4. x$⩾$y

Subtopic:  Enthalpy & Internal energy |
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In the reaction, $∆$H and $∆$S both are positive. The condition under which the reaction would not be spontaneous is -

1. $∆$H>T$∆$S

2. $∆$S=$∆$H/T

3. $∆$H=T$∆$S

4. All of the above

Subtopic:  Gibbs Energy Change |
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When an ideal gas is compressed adiabatically and reversibly, the final temperature is:

1. higher than the initial temperature

2. lower than the initial temperature

3. the same as the initial temperature

4. dependent on the rate of compression

Subtopic:  First Law of Thermodynamics |
57%
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1 liter-atmosphere is equal to:

1. 101.3 J

2. 24.20 cal

3. 101.3 x 107 erg

4. All of the above

Subtopic:  First Law of Thermodynamics |
69%
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The standard change is Gibbs energy for the reaction,

H2O$⇄$H+ + OH- at 25$°$C is:

1. 100 kJ

2. -90 kJ

3. 90 kJ

4. -100 kJ

Subtopic:  Spontaneity & Entropy |
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The entropy change in the fusion of one mole of a solid melting at 27$°$C  is:

(the latent heat of fusion is 2930 J mol-1)

1. 9.77 JK-1mol-1

2. 19.73 JK-1mol-1

3. 2930 JK-1mol-1

4. 108.5 JK-1mol-1

Subtopic:  Spontaneity & Entropy |
80%
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