The direct conversion of A to B is difficult and thus it is converted by path A$\to$C$\to$D$\to$B. Given

$∆{\mathrm{S}}_{\mathrm{A}\to \mathrm{C}}=50 \mathrm{e}.\mathrm{u}; ∆{\mathrm{S}}_{\mathrm{C}\to \mathrm{D}}=30 \mathrm{e}.\mathrm{u}; ∆{\mathrm{S}}_{\mathrm{B}\to \mathrm{D}}=20 \mathrm{e}.\mathrm{u}.$

(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

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)$\rightleftharpoons$ 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

Enthalpy of the reaction,

CH₄(g) + 1/2O₂(g) $\to$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

In the reaction, both $∆$H and $∆$S are positive. The condition(s) under which the reaction would not be spontaneous are/is:

1. $∆$H>T$∆$S                             

2. $∆$S=$∆$H/T

3. $∆$H=T$∆$S                               

4. All of the above

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

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

The standard change is Gibbs energy for the reaction,

H₂O$\rightleftarrows$H⁺ + OH^- at 25$°$C is:

1. 100 kJ                         

2. -90 kJ

3. 90 kJ                           

4. -100 kJ

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          

The maximum work done in expanding 16 g of oxygen at 300 K and occupying a volume of 5 dm³ isothermally until the volume becomes 25 dm³ is:

1. -2.01 x 10³ J                       

2. 2.81 x 10³ J

3. 2.01 x 10^-3 J                     

4. -2.01 x 10^-6 J