# PCl5, PCl3, and Cl2 are at equilibrium at 500 K in a closed container and their concentrations are 0.8×10–3 mol L–1 , 1.2×10–3 mol L–1 and 1.2×10–3 mol L–1, respectively. The value of  Kc  for the reaction PCl5(g) ⇌ PCl3(g) + Cl2(g) will be: 1. 1.8 × 103 mol L–1 2. 1.8 × 103 3. 1.8 × 10–3 mol L–1 4. 0.55 × 104

Subtopic:  Kp, Kc & Factors Affecting them |
88%
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An incorrect statement about equilibrium among the following is:

 1 In equilibrium mixture of ice and water kept in perfectly insulated flask, the mass of ice and water does not change with time. 2 The intensity of the red colour increases when oxalic acid is added to a solution containing iron (III) nitrate and potassium thiocyanate. 3 On the addition of a catalyst, the equilibrium constant value is not affected. 4 The equilibrium constant for a reaction with a negative  ∆H  value decreases as the temperature increases.
Subtopic:  Introduction To Equilibrium |
54%
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When hydrochloric acid is added to cobalt nitrate solution at room temperature, the following reaction takes place and the reaction mixture becomes blue. On cooling the mixture it becomes pink
$$[Co(H_2O)_6]^{3+} (aq) + 4Cl^-(aq) \rightleftharpoons [CoCl_4]^{2-} (aq) + 6H_2O(l)\\ ~~~\small{(Pink})~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\small{ (Blue)}$$

On the basis of the information given above, mark the correct answer:

 1 ∆ H > 0  for the reaction 2 ∆ H < 0  for the reaction 3 ∆ H = 0  for the reaction 4 The sign of  ∆ H  cannot be predicted on the basis of the given information.
Subtopic:  Le Chatelier's principle |
58%
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The pH of neutral water at $25°\mathrm{C}$ is 7.0. As the temperature increases, ionisation of water increases. However, the concentration of H+ ions and OH- ions is equal. What will be the pH of pure water at 60°C ?

 1 Equal to 7.0 2 Greater than 7.0 3 Less than 7.0 4 Equal to zero
Subtopic:  pH calculation |
64%
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The ionisation constant of an acid, Ka , is the measure of the strength of an acid. The Ka values of acetic acid, hypochlorous acid and formic acid are  and $1.8×{10}^{-4}$ , respectively. The  correct order of pH value of 0.1 mol dm-3 solutions of these acids is:

1. Acetic acid > Hypochlorous acid > Formic acid

2. Hypochlorous acid < Acetic acid > Formic acid

3. Formic acid > Hypochlorous acid > Acetic acid

4. Formic acid < Acetic acid < Hypochlorous acid

Subtopic:  pH calculation |
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${\mathrm{K}}_{{\mathrm{a}}_{1}},$ ${\mathrm{K}}_{{\mathrm{a}}_{2}}$ $\mathrm{and}$ ${\mathrm{K}}_{{\mathrm{a}}_{3}}$ are the respective ionisation constants for the following reactions.
$$\mathrm{H}_2 \mathrm{~S} \rightleftharpoons \mathrm{H}^{+}+\mathrm{HS}^{-}$$
$$\mathrm{HS}^{-} \rightleftharpoons \mathrm{H}^{+}+\mathrm{S}^{2-}$$
$$\mathrm{H}_2 \mathrm{~S} \rightleftharpoons 2 \mathrm{H}^{+}+\mathrm{S}^{2-}$$
The correct relationship between ${\mathrm{K}}_{{\mathrm{a}}_{1}},$ ${\mathrm{K}}_{{\mathrm{a}}_{2}}$ $\mathrm{and}$ ${\mathrm{K}}_{{\mathrm{a}}_{3}}$ is:
1. $$\mathrm{K}_{\mathrm{a}_3}=\mathrm{K}_{\mathrm{a}_1} \times \mathrm{K}_{\mathrm{a}_2}$$
2. $$\mathrm{K}_{\mathrm{a}_3}=\mathrm{K}_{\mathrm{a}_1}+\mathrm{K}_{\mathrm{a}_2}$$
3. $$K_{a_3}=K_{a_1}-K_{a_2}$$
4. $$\mathrm{K}_{\mathrm{a}_3}=\mathrm{K}_{\mathrm{a}_1} / \mathrm{K}_{\mathrm{a}_2}$$

Subtopic:  Introduction To Equilibrium |
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Acidity of BF3 can be explained on the basis of:

1. Arrhenius concept

2. Bronsted Lowry concept

3. Lewis concept

4. Bronsted Lowry as well as Lewis concept

Subtopic:  Acids & Bases - Definitions & Classification |
78%
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The mixture that will produce a buffer solution when mixed in equal volumes is:

 1 0.1 mol dm-3 NH4OH and 0.1 mol dm-3 HCl 2 0.05 mol dm-3 NH4OH and 0.1 mol dm-3 HCl 3 0.1 mol dm-3 NH4OH and 0.05 mol dm-3 HCl 4 0.1 mol dm-3 CH3COONa and 0.1 mol dm-3 NaOH

Subtopic:  Buffer |
60%
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Among the following solvents, silver chloride is most soluble in:

1.  solution

2.  solution

3. ${\mathrm{H}}_{2}\mathrm{O}$

4. Aqueous ammonia

Subtopic:  Common Ion Effect |
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The value of the pH of $$0.01$$ $$\text{mol dm}^{-3}$$$$\text{CH}_3\text{COOH}$$ $$\left(K_a=1.74 \times 10^{-5}\right)$$  is:

 1 3.4 2 3.6 3 3.9 4 3
Subtopic:  pH calculation |
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