Ncert Solutions Chemistry Class 11th
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Discuss briefly de-mineralisation of water by ion exchange resin.
Discuss briefly de-mineralisation of water by ion exchange resin.
This is a short answer type question as classified in NCERT Exemplar
Water demineralization using organic or synthetic ion exchange resins (ion exchange resins):
a. Synthetic resins are insoluble polymeric solids that contain a large hydrocarbon network with reactive acidic or basic groups.
Upvote 
The ionisation constant of an acid, Ka , is the measure of strength of an acid. The Ka values of acetic acid, hypochlorous acid and formic acid are 1.74 × 10–5, 3.0 × 10–8 and 1.8 × 10–4 respectively. Which of the following orders of pH of 0.1 mol dm–3 solutions of these acids is correct?
(i) Acetic acid > hypochlorous acid > formic acid
(ii) Hypochlorous acid > acetic acid > formic acid
(iii) Formic acid > hypochlorous acid > acetic acid
(iv) Formic acid > acetic acid > hypochlorous acid
The ionisation constant of an acid, Ka , is the measure of strength of an acid. The Ka values of acetic acid, hypochlorous acid and formic acid are 1.74 × 10–5, 3.0 × 10–8 and 1.8 × 10–4 respectively. Which of the following orders of pH of 0.1 mol dm–3 solutions of these acids is correct?
(i) Acetic acid > hypochlorous acid > formic acid
(ii) Hypochlorous acid > acetic acid > formic acid
(iii) Formic acid > hypochlorous acid > acetic acid
(iv) Formic acid > acetic acid > hypochlorous acid
This is a Multiple Choice Questions as classified in NCERT Exemplar
Ans: option (iv)
Higher the value of Ka higher will be the acidic strength Ka value for formic acid is the highest and that will be of hypochlorous acid is the lowest.
Upvote What do you understand about the term ‘autoprotolysis of water’? What is its significance?
What do you understand about the term ‘autoprotolysis of water’? What is its significance?
This is a short answer type question as classified in NCERT Exemplar
Self ionization of water is known as autoprotolysis of water.
H2O (l) + H2O (l) → H2O2 (aq
Upvote The pH of neutral water at 25°C is 7.0. As the temperature increases, ionisation of water increases, however, the concentration of H+ ions and OH– ions are equal. What will be the pH of pure water at 60°C?
(i) Equal to 7.0
(ii) Greater than 7.0
(iii) Less than 7.0
(iv) Equal to zero
The pH of neutral water at 25°C is 7.0. As the temperature increases, ionisation of water increases, however, the concentration of H+ ions and OH– ions are equal. What will be the pH of pure water at 60°C?
(i) Equal to 7.0
(ii) Greater than 7.0
(iii) Less than 7.0
(iv) Equal to zero
This is a Multiple Choice Questions as classified in NCERT Exemplar
Ans: As Kw increases Ans: As Kw increases [H+] [OH-] 10-14
[H+]= [OH-]
[H+]= [OH-] [H+]2 = 110-14
[H+] 10-7
Upvote 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. On the basis of this information mark the correct answer.
[Co (H2O)6] 3+ (aq) + 4Cl– (aq) ⇌ [CoCl4]2– (aq) + 6H2O (l)
(pink) (blue)
(i) ∆H > 0 for the reaction
(ii) ∆H < 0 for the reaction
(iii) ∆H = 0 for the reaction
(iv) The sign of ∆H cannot be predicted on the basis of this information.
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. On the basis of this information mark the correct answer.
[Co (H2O)6] 3+ (aq) + 4Cl– (aq) ⇌ [CoCl4]2– (aq) + 6H2O (l)
(pink) (blue)
(i) ∆H > 0 for the reaction
(ii) ∆H < 0 for the reaction
(iii) ∆H = 0 for the reaction
(iv) The sign of ∆H cannot be predicted on the basis of this information.
This is a Multiple Choice Questions as classified in NCERT Exemplar
Ans: option (i)
On cooling the mixture reaction moves towards backward direction it means it is an endothermic reaction i.e.,
Upvote Which of the following statements is incorrect?
(i) In equilibrium mixture of ice and water kept in perfectly insulated flask mass of ice and water does not change with time.
(ii) The intensity of red colour increases when oxalic acid is added to a solution containing iron
(III) nitrate and potassium thiocyanate.
(iii) On addition of catalyst the equilibrium constant value is not affected.
(iv) Equilibrium constant for a reaction with negative ?H value decreases as the temperature increases.
Which of the following statements is incorrect?
(i) In equilibrium mixture of ice and water kept in perfectly insulated flask mass of ice and water does not change with time.
(ii) The intensity of red colour increases when oxalic acid is added to a solution containing iron
(III) nitrate and potassium thiocyanate.
(iii) On addition of catalyst the equilibrium constant value is not affected.
(iv) Equilibrium constant for a reaction with negative ?H value decreases as the temperature increases.
This is a Multiple Choice Questions as classified in NCERT Exemplar
Ans: option (ii)
The intensity of red colour increases when oxalic acid is added to a solution containing iron (III) nitrate and potassium thiocyanate.
Iron (III) nitrate and potassium thiocyanate react to give deep red coloratio
Upvote Give reasons:
(i) Lakes freeze from top towards bottom.
(ii) Ice floats on water.
Give reasons:
(i) Lakes freeze from top towards bottom.
(ii) Ice floats on water.
(i) During winter, the temperature of lake water keeps on decreasing. Since cold water is heavier, it moves towards the bottom.
(ii) Density of ice is less than that of water that is why it floats on the surface of water.
Upvote PCl5, PCl3 and Cl2 are at equilibrium at 500K 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
(i) 1.8 × 103 mol L–1
(ii) 1.8 × 10–3
(iii) 1.8 × 10–3 L mol–1
(iv) 0.55 × 104
PCl5, PCl3 and Cl2 are at equilibrium at 500K 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
(i) 1.8 × 103 mol L–1
(ii) 1.8 × 10–3
(iii) 1.8 × 10–3 L mol–1
(iv) 0.55 × 104
This is a Multiple Choice Questions as classified in NCERT Exemplar
Ans: The given reaction is :-
PCl5(g)?PCl3(g)+Cl2(g)
KC=
=1.2×10−3 ×1.2×10−3 0.8×10−3
=1.8×10−3molL−1
Upvote Which of the following is not a general characteristic of equilibria involving physical processes?
(i) Equilibrium is possible only in a closed system at a given temperature.
(ii) All measurable properties of the system remain constant.
(iii) All the physical processes stop at equilibrium.
(iv) The opposing processes occur at the same rate and there is dynamic but stable condition.
Which of the following is not a general characteristic of equilibria involving physical processes?
(i) Equilibrium is possible only in a closed system at a given temperature.
(ii) All measurable properties of the system remain constant.
(iii) All the physical processes stop at equilibrium.
(iv) The opposing processes occur at the same rate and there is dynamic but stable condition.
This is a Multiple Choice Questions as classified in NCERT Exemplar
Ans: option (iii)
A physical equilibrium is having dynamic nature, both forward and reverse process occur at equal rates. Some kind of motion is always present. The individual molecules continuously move from one phase to another.
Upvote Which of the following is not a general characteristic of equilibria involving physical processes?
(i) Equilibrium is possible only in a closed system at a given temperature.
(ii) All measurable properties of the system remain constant.
(iii) All the physical processes stop at equilibrium.
(iv) The opposing processes occur at the same rate and there is dynamic but stable condition.
Which of the following is not a general characteristic of equilibria involving physical processes?
(i) Equilibrium is possible only in a closed system at a given temperature.
(ii) All measurable properties of the system remain constant.
(iii) All the physical processes stop at equilibrium.
(iv) The opposing processes occur at the same rate and there is dynamic but stable condition.
This is a Multiple Choice Questions as classified in NCERT Exemplar
Ans: option (iii)
A physical equilibrium is having dynamic nature, both forward and reverse process occur at equal rates. Some kind of motion is always present. The individual molecules continuously move from one phase to another.
Upvote