A sample containing 1.0 mol of an ideal gas is expanded isothermally and reversible to ten times of its original volume in two separate experiments. The expansion is carried out at 300 K and at 600 K respectively.
The correct statements among the following are:
(a) | Work done at 600 K is 20 times the work done at 300 K. |
(b) | Work done at 300 K is twice the work done at 600 K. |
(c) | Work done at 600 K is twice the work done at 300 K. |
(d) | ∆ U = 0 in both cases. |
1. (a, b)
2. (b, c)
3. (c, d)
4. (a, d)
The correct statements among the following are :
a. | The enthalpy of two moles of ZnO is less than the total enthalpy of two moles of Zn and one mole of oxygen by 693.8 kJ |
b. | The enthalpy of two moles of ZnO is more than the total enthalpy of two moles of Zn and one mole of oxygen by 693.8 kJ |
c. | 693 . 8 kJ mol -1 energy is evolved in the reaction |
d. | 693 . 8 kJ mol -1 energy is absorbed in the reaction |
1. (a, b)
2. (b, c)
3. (c, d)
4. (a, c)
The processes among the following that occur spontaneously are :
(a) | The flow of heat from a colder to a warmer body. |
(b) | Gas in a container contracting into one corner. |
(c) | Gas expanding to fill the available volume. |
(d) | Burning carbon in oxygen to give carbon dioxide. |
1. (a, b)
2. (b, c)
3. (c, d)
4. (a, d)
In an exothermic reaction, heat is evolved, and the system loses heat to the surrounding. The correct choice among the following for such a system are-
(a) qp will be negative
(b) will be negative
(c) qp will be positive
(d) will be positive
1. (a, b)
2. (b, c)
3. (c, d)
4. (a, d)
Thermodynamics mainly deals with-
(a) | Interrelation of various forms of energy and their transformation from one form to another. |
(b) | Energy changes in the processes depend only on the initial and final states of the microscopic systems containing a few molecules. |
(c) | How and at what rate these energy transformations are carried out. |
(d) | The system is in an equilibrium state or moving from one equilibrium state to another equilibrium state. |
The correct choice among the above is:
1. (a, b)
2. (b, c)
3. (c, d)
4. (a, d)
Which of the following is not correct?
1. is zero for a reversible reaction.
2. is positive for a spontaneous reaction.
3. is negative for a spontaneous reaction.
4. is positive for a non-spontaneous reaction.
The enthalpy of sublimation of a substance is equal to:
1. Enthalpy of fusion + Enthalpy of vaporization
2. Enthalpy of fusion
3. Enthalpy of vaporization
4. Twice the enthalpy of vaporization
The enthalpies of elements in their standard states are taken as zero. The enthalpy of formation of a compound is-
1. | Generally negative | 2. | Always positive |
3. | Zero | 4. | Never negative |
Based on the reactions, ascertain the valid algebraic relationship:
1. | x = y | 2. | x = 2y |
3. | x > y | 4. | x < y |
On the basis of thermochemical equations (i), (ii), and (iii), find out which of the algebraic relationships given in options (a) to (d) is correct:
(i) | C(graphite) + O2(g) → CO2 (g) ; ∆rH = x kJmol-1 |
(ii) | C(graphite) + \(\frac{1}{2}\)O2(g) → CO(g) ; ∆rH = y kJ mol-1 |
(iii) | CO(g) + \(\frac{1}{2}\)O2(g) → CO2(g); ∆rH = z kJ mol-1 |
1. z=x+y
2. x=y-z
3. x=y+z
4. y=2z-x