Define the following:
(i) First law of thermodynamics.
(ii) Standard enthalpy of formation.

Give reason for the following:
(a)Neither q nor w is a state function but q + w is a state function.
(b)A real crystal has more entropy than an ideal crystal.

(a)What is a spontaneous process? Mention the conditions for a reaction to be spontaneous at constant temperature and pressure.
(b) Discuss the effect of temperature on the spontaneity of an exothermic reaction

 Predict in which of the following, entropy increases/decreases.
(i) A liquid crystallizes into a solid
(ii) Temperature of a crystallize solid is raised from OK to 115 K
(iii) 2NaHCO₃ (s) ———-> Na₂ C0₃ (s) + C0₂ (g) + H₂O (g)
(iv) H₂(g)——>2H(g)

Why standard entropy of an elementary substance is not zero whereas standard enthalpy of formation is taken as zero?
Under what conditions will the reaction occur, if
(i) both ∆H and ∆S are positive
(ii) both ∆H and ∆S are negative

 What is bond energy? Why is it called enthalpy of atomisation?
(b) Calculate the bond energy of C-H bond, given that the heat of formation of CH₄, heat of sublimation of carbon and heat of dissociation of H₂ are – 74.8, + 719.6, 435.4 kj mol^-1 respectively.

 Thermodynamics is applicable to
(a) macroscopic system only (b) microsopic system only
(c) homogeneous system only (d) heterogeneous system only

 An isochoric process takes place at constant
(a) temperature (b) pressure
(c) volume (d) concentration

 For a cyclic process, the change in internal energy of the system is
(A) always +ve (b) equal to zero
(c) always -ve (d) none of the above

Which of the following properties is not a function of state?
(a) concentration (b) internal energy
(c) enthalpy (d) entropy

 Which of the following always has a negative value?
(a) heat of reaction (b) heat of solution
(c) heat of combustion (d) heat of formation