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Q. No.40% HI undergoes decomposition to form H₂ and I₂ at 300 K. Find the value of ΔG° for this decomposition reaction at 1 atm pressure in J mol⁻¹ (nearest integer).
(R = 8.31 J K⁻¹ mol⁻¹)
1. 2720
2. 2740
3. 2640
4. 2520
Subtopic: Common Ion Effect |
Level 3: 35%-60%
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\(\mathrm{K}_{\mathrm{a}_1}, \mathrm{~K}_{\mathrm{a}_2} \text { and } \mathrm{K}_{\mathrm{a}_3}\) are the respective ionization constants for the following reactions \(\mathrm{(a),(b)~and~(c).}\)
\(\mathrm{(a)}~ \mathrm{H}_2 \mathrm{C}_2 \mathrm{O}_4 \rightleftharpoons \mathrm{H}^{+}+\mathrm{HC}_2 \mathrm{O}_4^{-}\\ \mathrm{(b)}~ \mathrm{HC}_2 \mathrm{O}_4^{-} \rightleftharpoons \mathrm{H}^{+}+\mathrm{C}_2 \mathrm{O}_4^{2-}\\ \mathrm{(c)}~ \mathrm{H}_2 \mathrm{C}_2 \mathrm{O}_4 \rightleftharpoons 2 \mathrm{H}^{+}+\mathrm{C}_2 \mathrm{O}_4^{2-}\)
The relationship between \(\mathrm{K}_{\mathrm{a}_1}, \mathrm{~K}_{\mathrm{a}_2} \text { and } \mathrm{K}_{\mathrm{a}_3}\) is given as:
\(\mathrm{(a)}~ \mathrm{H}_2 \mathrm{C}_2 \mathrm{O}_4 \rightleftharpoons \mathrm{H}^{+}+\mathrm{HC}_2 \mathrm{O}_4^{-}\\ \mathrm{(b)}~ \mathrm{HC}_2 \mathrm{O}_4^{-} \rightleftharpoons \mathrm{H}^{+}+\mathrm{C}_2 \mathrm{O}_4^{2-}\\ \mathrm{(c)}~ \mathrm{H}_2 \mathrm{C}_2 \mathrm{O}_4 \rightleftharpoons 2 \mathrm{H}^{+}+\mathrm{C}_2 \mathrm{O}_4^{2-}\)
The relationship between \(\mathrm{K}_{\mathrm{a}_1}, \mathrm{~K}_{\mathrm{a}_2} \text { and } \mathrm{K}_{\mathrm{a}_3}\) is given as:
| 1. | \(\mathrm{K}_{\mathrm{a}_3}=\mathrm{K}_{\mathrm{a}_1}+\mathrm{K}_{\mathrm{a}_2} \) | 2. | \(\mathrm{K}_{\mathrm{a}_3}=\mathrm{K}_{\mathrm{a}_1}-\mathrm{K}_{\mathrm{a}_2} \) |
| 3. | \(\mathrm{K}_{\mathrm{a}_3}=\mathrm{K}_{\mathrm{a}_1} / \mathrm{K}_{\mathrm{a}_2} \) | 4. | \(\mathrm{K}_{\mathrm{a}_3}=\mathrm{K}_{\mathrm{a}_1} \times \mathrm{K}_{\mathrm{a}_2}\) |
Subtopic: pH calculation |
74%
Level 2: 60%+
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Given below are two statements:
| Assertion (A): | The amphoteric nature of water is explained by using Lewis acid/base concept. |
| Reason (R): | Water acts as an acid with \(\mathrm {NH}_3\) and as a base with \(\mathrm {H_2S}\). |
| 1. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
| 2. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
| 3. | (A) is True but (R) is False. |
| 4. | (A) is False but (R) is True. |
Subtopic: Acids & Bases - Definitions & Classification |
54%
Level 3: 35%-60%
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At \(\mathrm{298~K},\) The equilibrium constant is \(2 \times10^{15}\) for the reaction: \(\mathrm{Cu}(\mathrm{s})+2 \mathrm{Ag}^{+}(\mathrm{aq}) \rightleftharpoons \mathrm{Cu}^{2+}(\mathrm{aq})+2 \mathrm{Ag}(\mathrm{s})\).
If the equilibrium constant for the reaction \(\frac{1}{2} \mathrm{Cu}^{2+}(\mathrm{aq})+\mathrm{Ag}(\mathrm{s}) \rightleftharpoons \frac{1}{2} \mathrm{Cu}(\mathrm{s})+\mathrm{Ag}^{+}(\mathrm{aq})\) is \(x \times 10^{-8}\), then find the value of \(\mathrm{x}\) in nearest integer form:
1. Eight (8)
2. Five (5)
3. Six (6)
4. Two (2)
If the equilibrium constant for the reaction \(\frac{1}{2} \mathrm{Cu}^{2+}(\mathrm{aq})+\mathrm{Ag}(\mathrm{s}) \rightleftharpoons \frac{1}{2} \mathrm{Cu}(\mathrm{s})+\mathrm{Ag}^{+}(\mathrm{aq})\) is \(x \times 10^{-8}\), then find the value of \(\mathrm{x}\) in nearest integer form:
1. Eight (8)
2. Five (5)
3. Six (6)
4. Two (2)
Subtopic: Ionisation Constant of Acid, Base & Salt |
69%
Level 2: 60%+
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\(2 \mathrm{NOCl}(\mathrm{g}) \rightleftharpoons 2 \mathrm{NO}(\mathrm{g})+\mathrm{Cl}_2(\mathrm{~g})\)
In an experiment, \(2.0\) moles of \(\mathrm{NOCl}\) was placed in a one-litre flask and the concentration of NO after equilibrium established, was found to be \(0.4 ~\text{mol/ L.}\) . The equilibrium constant at \(30^\circ \text{C}\) is \(x × 10^{–4} \), then value of \(x\) is :
1. 120
2. 125
3. 140
4. 145
In an experiment, \(2.0\) moles of \(\mathrm{NOCl}\) was placed in a one-litre flask and the concentration of NO after equilibrium established, was found to be \(0.4 ~\text{mol/ L.}\) . The equilibrium constant at \(30^\circ \text{C}\) is \(x × 10^{–4} \), then value of \(x\) is :
1. 120
2. 125
3. 140
4. 145
Subtopic: Kp, Kc & Factors Affecting them |
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Level 1: 80%+
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Class XII students were asked to prepare one litre of buffer solution of pH 8.26 by their Chemistry teacher. The amount of ammonium chloride to be dissolved by the student in \(\mathrm{0.2 ~M}\) ammonia solution to make one litre of the buffer is :
\((Given : \mathrm{pK}_{\mathrm{b}}\left(\mathrm{NH}_3\right)=4.74, \text{Molar mass of }~\mathrm{NH}_3=17 \mathrm{g} \mathrm{mol}^{-1}, \text{Molar mass of}~ \mathrm{NH}_4 \mathrm{Cl}=53.5 \mathrm{~g} \mathrm{~mol}^{-1} )\)
1. \(\mathrm{5.30~g}\)
2. \(\mathrm{72.3~g}\)
3. \(\mathrm{107.0~g}\)
4. \(\mathrm{126.0~g}\)
Subtopic: Buffer |
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Level 2: 60%+
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What is the pH of 0.2 M solution of butyric acid if Ka for butyric acid (C3H7COOH) is 2 × 10–5 ?
[Given: log2 = 0.30]
1. 2.1
2. 2.4
3. 2.7
4. 2.9
[Given: log2 = 0.30]
1. 2.1
2. 2.4
3. 2.7
4. 2.9
Subtopic: pH calculation |
84%
Level 1: 80%+
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Given below are two statements:
| Assertion (A): | Phenolphthalein is a pH dependent indicator, remains colourless in acidic solution and gives pink colour in basic medium. |
| Reason (R): | Phenolphthalein is a weak acid. It doesn’t dissociate in basic medium. |
| 1. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
| 2. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
| 3. | (A) is True but (R) is False. |
| 4. | (A) is False but (R) is True. |
Subtopic: Salt Hydrolysis & Titration |
70%
Level 2: 60%+
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A student needs to prepare a buffer solution of propanoic acid and its sodium salt with pH = 4. The ratio of \(\frac{\left[\mathrm{CH}_3 \mathrm{CH}_2 \mathrm{COO}^{-}\right]}{\left[\mathrm{CH}_3 \mathrm{CH}_2 \mathrm{COOH}\right]}\)required to make a buffer is:
Given : \(\mathrm{K}_{\mathrm{a}}\left(\mathrm{CH}_3 \mathrm{CH}_2 \mathrm{COOH}\right)=1.3 \times 10^{-5} \)
1. 0.03
2. 0.13
3. 0.23
4. 0.33
Given : \(\mathrm{K}_{\mathrm{a}}\left(\mathrm{CH}_3 \mathrm{CH}_2 \mathrm{COOH}\right)=1.3 \times 10^{-5} \)
1. 0.03
2. 0.13
3. 0.23
4. 0.33
Subtopic: Buffer |
69%
Level 2: 60%+
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At \(310~ K,\) the solubility of \(\mathrm{CaF}_2\) in water is \(2.34 \times 10^{-3} \mathrm{~g} / 100 \mathrm{~ml} \text {. }\)
If the solubility product of \(\mathrm{CaF}_2\) is \(x \times 10^{-10}\), Find \(x\) :
[Given molar mass of \(\mathrm{CaF}_2=78 \mathrm{~g} \mathrm{~mol}^{-1}\) ]
1. 3.00
2. 1.08
3. 0.01
4. 7.20
Subtopic: Solubility Product |
73%
Level 2: 60%+
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