Q. No.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)
What is the change in internal energy for 5 moles of an ideal gas when it undergoes reversible compression from 100 K to 200 K?
(Given CV = 28 J K–1 mol–1)
| 1. | ΔU = 8kJ | 2. | ΔU = 14kJ |
| 3. | ΔU = 10kJ | 4. | ΔU = 2.8 kJ |
| (i) | When liquid crystallizes into a solid, entropy increases. |
| (ii) | When the temperature of a crystalline solid is raised from 0 K to 115 K then entropy increases. |
| (iii) | 2 NaHCO3 (s) →Na2CO3 (s) +CO2(g)+H2O(g); Entropy increases. |
| (iv) | H2(g)→2H(g) ; Entropy decreases. |
The average S–F bond energy in kJ mol–1 of SF6 is:
[The values of standard enthalpy of formation of
SF6(g), S(g), and F(g) are –1100, 275, and 80 kJmol–1 respectively.]
| 1. | 309 kJ mol–1 | 2. | 313 kJ mol–1 |
| 3. | 305 kJ mol–1 | 4. | 318 kJ mol–1 |
Consider a cycle followed by an engine (figure).
1 to 2 is isothermal,
2 to 3 is adiabatic,
3 to 1 is adiabatic.
Such a process does not exist, because:
| (a) | heat is completely converted to mechanical energy in such a process, which is not possible. |
| (b) | In this process, mechanical energy is completely converted to heat, which is not possible. |
| (c) | curves representing two adiabatic processes don’t intersect. |
| (d) | curves representing an adiabatic process and an isothermal process don't intersect. |
Choose the correct alternatives:
| 1. | (a), (b) | 2. | (a), (c) |
| 3. | (b), (c) | 4. | (c), (d) |
The entropy change for the melting of 'x' moles of ice at 273 K and 1 atm pressure is 28.80 cal K–1.
The value of 'x' is:
(Given: heat of fusion is 80 cal g–1)
| 1. | 4.32 mol | 2. | 8.56 mol |
| 3. | 10.36 mol | 4. | 5.46 mol |
| 1. | \(4\) | 2. | \(1\) |
| 3. | \(2\) | 4. | \(3\) |
| Column I | Column II | ||
| (i) | Spontaneous process | (a) | Isothermal and isobaric process |
| (ii) | \(\Delta H^\circ\) | (b) | \(\Delta H<0 \) |
| (iii) | \(\Delta T=0, \Delta P=0 \) | (c) | \(\Delta G<0 \) |
| (iv) | Exothermic process | (d) | (Bond energy of reactant) - (Bond energy of product) |
| I | II | III | IV | |
| 1. | c | d | a | b |
| 2. | b | a | c | d |
| 3. | d | b | c | d |
| 4. | a | d | b | c |
The pressure and volume of a gas are changed as shown in the P-V diagram. The temperature of the gas will:
| 1. | increase as it goes from A to B. |
| 2. | increase as it goes from B to C. |
| 3. | remain constant during these changes. |
| 4. | decrease as it goes from D to A. |
(where symbols have their usual meanings)
1. \(C_P = \frac{\gamma R}{\gamma-1 }\)
2. \(C_P-C_V= R\)
3. \(\Delta U = \frac{P_fV_f-P_iV_i}{1-\gamma}\)
4. \(C_V = \frac{R}{\gamma-1 }\)
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