Thermodynamics

In which of the following process , maximum increase in entropy is observed ?

• Melting of ice

• Sublimation of naphthalene

• Condensation of water

• Dissolution of salt in water

For a reaction to be spontaneous at all temperatures ,

• $∆$G and $∆$H till should be negative

• $∆$G and $∆$H till should be positive

• $∆$G = $∆$S = 0

• $∆$H < $∆$G

The heat of formarion of CO₂ is - 393 kJ mol^-1 .The amount of heat evolved in the formation of 0.156 kg of CO₂ .

• - 1393 kJ

• + 1165.5 kJ

• + 1275.9 kJ

• - 1165.5 kJ

In an isobaric process, when temperature changes from T₁ to T₂ ,$∆$S is equal to

• 2.303 C_p log (T₂/T₁)

• 2.303 C_p ln (T₂/T₁)

• C_p ln (T₁/T₂)

• C_v ln (T₂/T₁)

Heat of neutralisation of an acid with a base is 13. 7 kcal when :

• both acid and base are weak

• acid is weak and base is strong

• both acid and base are strong

• acid is strong and base is weak

Hess's law is based on :

• law of conservation of mass

• law of conservation of energy

• enthalpy is a state function

• none of the above

Assertion : A reaction which is spontaneous and accompanied by decrease of randomness must be exothermic.

Reason : All exothermic reactions are accompanied by decrease of randomness.

• If both assertion and reason are true and reason is the correct explanation of assertion

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false

• If both assertion and reason are false

The enthalpy change ($∆$H) for the neutralisation of M HCl by caustic potash in dilute solution at 298 K is :

• 68 kJ

• 65 kJ

• 57.3 kJ

• 50 kJ

Calculate change in internal energy if $∆$H = - 92.2 kJ, P = 40 atm and $∆$V = -1L.

• -42 kJ

• -88 kJ

• +88 kJ

• +42 kJ

$∆$H_fusion of a substance is 'x' and $∆$H_vap is 'y', then $∆$H_sublimation will be

• x + y

• x - y

• x/y

• y/x