Q. No.The standard enthalpy of the formation of CH3OH(l) from the following data is:
\(\small{\mathrm{CH}_3 \mathrm{OH}_{(l)}+\frac{3}{2} \mathrm{O}_2(\mathrm{g}) \rightarrow \mathrm{CO}_2(\mathrm{g})+2 \mathrm{H}_2 \mathrm{O}_{(l)} \text {; }}\)
\( \Delta_{\mathrm{r}} \mathrm{H}^{\circ}=-726 \mathrm{~kJ} \mathrm{~mol}{ }^{-1}\)
\(\small{\mathrm{C}(\mathrm{s})+\mathrm{O}_2(\mathrm{g}) \rightarrow \mathrm{CO}_2(\mathrm{g}) \text {; } }\)
\(\Delta_{\mathrm{c}} \mathrm{H}^{\circ}=-393 \mathrm{~kJ} \mathrm{~mol}{ }^{-1}\)
\(\small{\mathrm{H}_{2(\mathrm{g})}+\frac{1}{2} \mathrm{O}_{2(\mathrm{g})} \rightarrow \mathrm{H}_2 \mathrm{O}_{(l)} \text {; } } \)
\(\Delta_{\mathrm{f}} \mathrm{H}^{\circ}=-286 \mathrm{~kJ} \mathrm{~mol}^{-1}\)
1.
−239 kJ mol−1
2.
+239 kJ mol−1
3.
−47 kJ mol−1
4.
+47 kJ mol−1
\( \Delta_{\mathrm{r}} \mathrm{H}^{\circ}=-726 \mathrm{~kJ} \mathrm{~mol}{ }^{-1}\)
\(\Delta_{\mathrm{c}} \mathrm{H}^{\circ}=-393 \mathrm{~kJ} \mathrm{~mol}{ }^{-1}\)
\(\Delta_{\mathrm{f}} \mathrm{H}^{\circ}=-286 \mathrm{~kJ} \mathrm{~mol}^{-1}\)
If for a certain reaction is 30 kJ mol–1 at 450 K, the value of (in JK–1 mol–1) for which the same reaction will be spontaneous at the same temperature is:
| 1. | 70 | 2. | –33 |
| 3. | 33 | 4. | –70 |
At standard conditions, if the change in the enthalpy for the following reaction is –109 kJ mol–1
H2(g)+Br2(g)2HBr(g) and the bond energy of H2 and Br2 is 435 kJ mol–1 and 192 kJ mol–1 respectively, what is the bond energy (in kJ mol–1) of HBr?
| 1. | 368 | 2. | 736 |
| 3. | 518 | 4. | 259 |
The amount of heat needed to raise the temperature of 60.0 g of aluminium from 35°C to 55°C would be:
(Molar heat capacity of Al is \(24\) \(J\) \(\text{mol}^{- 1}\) \(K^{- 1}\))
| 1. | \(1 . 07\) \(J\) | 2. | \(1 . 07\) \(kJ\) |
| 3. | \(106 . 7\) \(kJ\) | 4. | \(100 . 7\) \(kJ\) |
The enthalpy of formation of all elements in their standard state is-
| 1. | Unity | 2. | Zero |
| 3. | Less than zero | 4. | Different for each element |
The correct statement among the following is:
| 1. | The presence of reacting species in a covered beaker is an example of an open system. |
| 2. | There is an exchange of energy as well as matter between the system and the surroundings in a closed system. |
| 3. | The presence of reactants in a closed vessel made up of copper is an example of a closed system. |
| 4. | The presence of reactants in a thermos flask or any other closed insulated vessel is an example of a closed system. |
Match the following parameters with a description for spontaneity.
| \(\Delta r\ H^⊝\) | \(\Delta r\ S^⊝\) | \(\Delta r\ G^⊝\) | Description | ||
| A. | + | – | + | 1. | Non-spontaneous at high temperature |
| B. | – | – | + at high T | 2. | Spontaneous at all temperatures |
| C. | – | + | – | 3. | Non-spontaneous at all temperatures |
Codes:
| A | B | C | |
| 1. | 3 | 1 | 2 |
| 2. | 1 | 2 | 3 |
| 3. | 1 | 3 | 2 |
| 4. | 3 | 2 | 1 |
Match the following process with entropy change:
| Reaction | Entropy change | ||
| A. | A liquid vaporizes | 1. | |
| B. | Reaction is non-spontaneous at all temperatures and is positive | 2. | |
| C. | Reversible expansion of an ideal gas | 3. |
Codes:
| A | B | C | |
| 1. | 2 | 3 | 1 |
| 2. | 1 | 2 | 3 |
| 3. | 1 | 3 | 2 |
| 4. | 3 | 2 | 1 |
Given the reaction:
\(2 \mathrm{Cl}(\mathrm{~g}) \rightarrow \mathrm{Cl}_2(\mathrm{~g})\)
What are the values of \(∆\mathrm{H}\) and \(∆\mathrm{S}\), respectively?
1. \(\Delta \mathrm{H}=0, \Delta \mathrm{~S}=-\mathrm{ve}\)
2. \(\Delta \mathrm{H}=0, \Delta \mathrm{~S}=0\)
3. \(\Delta \mathrm{H}=-\mathrm{ve}, \Delta \mathrm{~S}=-\mathrm{ve}\)
4. \(\Delta \mathrm{H}=+\mathrm{ve}, \Delta \mathrm{~S}=+\mathrm{ve}\)
For the graph given below, it can be concluded that work done during the process shown will be-
| 1. | Zero | 2. | Negative |
| 3. | Positive | 4. | Cannot be determined |
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