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

 The bond energy depends upon
(a) size of the atom (b) electronegativity
(c) bond length (d) all of the above

For an endothermic reaction.
(a) ∆H is -ve (b) ∆H is +ve
(c) ∆H is zero (d) none of these

The process depicted by the equation.
H₂O (S) ——> H₂O (l) ∆H = +1.43 kcal represents
(a) fusion (b) melting
(c) evaporation (d) boilirtg

Which one is the correct unit for entropy?
(a) KJ mol (b)JK mol
(c)JK mol^-1 (d) KJ mol^-1