Q. No.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)
1 to 2 is isothermal,
2 to 3 is adiabatic,
3 to 1 is adiabatic.
Such a process does not exist, because:
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. \(C_V = \frac{R}{\gamma-1 }\)
1. \(0\)
2. \(5~\text{J}\)
3. \(1~\text{J}\)
4. \(3~\text{J}\)
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 |
Find out the total heat given to diatomic gas in the process \(A\rightarrow B \rightarrow C\): \(( B\rightarrow C\) is isothermal)
1. \(P_0V_0+ 2P_0V_0\ln 2\)
2. \(\frac{1}{2}P_0V_0+ 2P_0V_0\ln 2\)
3. \(\frac{5}{2}P_0V_0+ 2P_0V_0\ln 2\)
4. \(3P_0V_0+ 2P_0V_0\ln 2\)
The standard enthalpies of the formation of NO2(g) and N2O4(g) are 8 kcal mol–1 and 2 kcal mol–1 respectively. The heat of dimerization of NO2 in the gaseous state is:
| 1. | 10 k cal mol–1 | 2. | 6.0 k cal mol–1 |
| 3. | –14 k cal mol–1 | 4. | –6.0 k cal mol–1 |
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