Q1Multiple choice
We know that the relationship between Kc and Kp is ∆n Kp = Kc (RT) What would be the value of ∆n for the reaction NH4Cl (s) NH3 (g) + HCl (g)
- (i)1
- (ii)0.5
- (iii)1.5
- (iv)2
Show answer
(iv) 2
Chapter 7 – Equilibrium
Class 11 Chemistry · 54 questions · 51 with answers
Questions
Q2Multiple choice
For the reaction H2(g) + I2(g) 2HI (g), the standard free energy is ∆G > 0. The equilibrium constant (K ) would be __________.
- (i)K=0
- (ii)K>1
- (iii)K=1
- (iv)K<1
Show answer
(iv) K<1
Q3Multiple choice
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.
Show answer
(iii) All the physical processes stop at equilibrium.
Q4Multiple choice
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 3 –1
- (i)1.8 × 10 mol L –3
- (ii)1.8 × 10 –3 –1
- (iii)1.8 × 10 L mol
- (iv)0.55 × 10
Show answer
(ii) 1.8 × 10 –3 –1
Q5Multiple choice
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.
Show answer
(ii) The intensity of red colour increases when oxalic acid is added to a solution containing iron (III) nitrate and potassium thiocyanate.
Q6Multiple choice
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] (aq) + 4Cl (aq) [CoCl4] (aq) + 6H2O (l ) 3+ – 2– (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.
Show answer
(i) ∆H > 0 for the reaction
Q7Multiple choice
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
Show answer
(iii) Less than 7.0
Q8Multiple choice
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 –5 –8 –4 1.74 × 10 , 3.0 × 10 and 1.8 × 10 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 87 Equilibrium
- (iii)formic acid > hypochlorous acid > acetic acid
- (iv)formic acid > acetic acid > hypochlorous acid
Show answer
(iv) formic acid > acetic acid > hypochlorous acid
Q9Multiple choice
K a , K a and K a are the respective ionisation constants for the following 1 2 3 reactions. H S H + HS + – HS H + S – + 2– + 2– H2S 2H + S The correct relationship between K a1 , K a 2 and K a 3 is
- (i)K a = Ka × K a 3 1 2
- (ii)K a = Ka + K a 3 1 2
- (iii)K a = Ka – K a 3 1 2
- (iv)K a = Ka / K a 3 1 2
Show answer
(i) K a = Ka × K a 3 1 2
Q10Multiple choice
Acidity of BF3 can be explained on the basis of which of the following concepts?
- (i)Arrhenius concept
- (ii)Bronsted Lowry concept
- (iii)Lewis concept
- (iv)Bronsted Lowry as well as Lewis concept.
Show answer
(iii) Lewis concept
Q11Multiple choice
Which of the following will produce a buffer solution when mixed in equal volumes?
- (i)0.1 mol dm–3 NH4OH and 0.1 mol dm–3 HCl
- (ii)0.05 mol dm–3 NH4OH and 0.1 mol dm–3 HCl
- (iii)0.1 mol dm–3 NH4OH and 0.05 mol dm–3 HCl
- (iv)0.1 mol dm–3 CH4COONa and 0.1 mol dm–3 NaOH
Show answer
(iii) 0.1 mol dm–3 NH4OH and 0.05 mol dm–3 HCl
Q12Multiple choice
In which of the following solvents is silver chloride most soluble?
- (i)0.1 mol dm–3 AgNO3 solution
- (ii)0.1 mol dm–3 HCl solution
- (iii)H2O
- (iv)Aqueous ammonia –5
Show answer
(iv) Aqueous ammonia –5
Q13Multiple choice
What will be the value of pH of 0.01 mol dm–3 CH3COOH (Ka = 1.74 × 10 )?
- (i)3.4
- (ii)3.6
- (iii)3.9
- (iv)3.0 –5 –5
Show answer
(i) 3.4
Q14Multiple choice
Ka for CH3COOH is 1.8 × 10 and K b for NH4OH is 1.8 × 10 . The pH of ammonium acetate will be
- (i)7.005
- (ii)4.75
- (iii)7.0
- (iv)Between 6 and 7
Show answer
(iii) 7.0
Q15Multiple choice
Which of the following options will be correct for the stage of half completion of the reaction A B.
- (i)∆G = 0
- (ii)∆G > 0
- (iii)∆G < 0
- (iv)∆G = –RT ln2
Show answer
(i) ∆G = 0
Hint: A] = [B
Q16Multiple choice
On increasing the pressure, in which direction will the gas phase reaction proceed to re-establish equilibrium, is predicted by applying the Le Chatelier’s principle. Consider the reaction. N2 (g) + 3H2 (g) 2NH3 (g) Which of the following is correct, if the total pressure at which the equilibrium is established, is increased without changing the temperature?
- (i)K will remain same
- (ii)K will decrease
- (iii)K will increase
- (iv)K will increase initially and decrease when pressure is very high
Show answer
(i) K will remain same
Q17Multiple choice
What will be the correct order of vapour pressure of water, acetone and ether at 30°C. Given that among these compounds, water has maximum boiling point and ether has minimum boiling point?
- (i)Water < ether < acetone
- (ii)Water < acetone < ether
- (iii)Ether < acetone < water
- (iv)Acetone < ether < water
Show answer
(ii) Water < acetone < ether
Q18Multiple choice
At 500 K, equilibrium constant, Kc , for the following reaction is 5. 1 1 H2 (g) + I2 (g) HI (g) 2 2 What would be the equilibrium constant Kc for the reaction 2HI (g) H2 (g) + I2 (g) 89 Equilibrium
- (i)0.04
- (ii)0.4
- (iii)25
- (iv)2.5
Show answer
(i) 0.04
Q19Multiple choice
In which of the following reactions, the equilibrium remains unaffected on addition of small amount of argon at constant volume?
- (i)H2 (g) + I2 (g) 2HI (g)
- (ii)PCl5 (g) PCl3 (g) + Cl2 (g)
- (iii)N2 (g) + 3H2 (g) 2NH3 (g)
- (iv)The equilibrium will remain unaffected in all the three cases.
Show answer
(iv) The equilibrium will remain unaffected in all the three cases.
Q20Multiple correct
For the reaction N2O4 (g) 2NO2 (g), the value of K is 50 at 400 K and 1700 at 500 K. Which of the following options is correct?
- (i)The reaction is endothermic
- (ii)The reaction is exothermic
- (iii)If NO2 (g) and N2O4 (g) are mixed at 400 K at partial pressures 20 bar and 2 bar respectively, more N2O4 (g) will be formed.
- (iv)The entropy of the system increases.
Show answer
(i) The reaction is endothermic
(iii) If NO2 (g) and N2O4 (g) are mixed at 400 K at partial pressures 20 bar and 2 bar respectively, more N2O4 (g) will be formed.
(iv) The entropy of the system increases.
Q21Multiple correct
At a particular temperature and atmospheric pressure, the solid and liquid phases of a pure substance can exist in equilibrium. Which of the following term defines this temperature?
- (i)Normal melting point
- (ii)Equilibrium temperature
- (iii)Boiling point
- (iv)Freezing point
Show answer
(i) Normal melting point
(iv) Freezing point
Q22Short answer
The ionisation of hydrochloric in water is given below: HCl(aq) + H2O (l ) H3O (aq) + Cl (aq) + – Label two conjugate acid-base pairs in this ionisation.
Show answer
HCl Cl acid conjugate base + H2O H3O base conjugate acid
Q23Short answer
The aqueous solution of sugar does not conduct electricity. However, when sodium chloride is added to water, it conducts electricity. How will you explain this statement on the basis of ionisation and how is it affected by concentration of sodium chloride?
Show answer
• Sugar does not ionise in water but NaCl ionises completely in water + – and produces Na and Cl ions. • Conductance increases with increase in concentration of salt due to release of more ions. 97 Equilibrium
Q24Short answer
BF3 does not have proton but still acts as an acid and reacts with NH3. Why is it so? What type of bond is formed between the two?
Show answer
BF3 acts as a Lewis acid as it is electron deficient compound and coordinate bond is formed as given below : H3N : → BF3
Q25Short answer
Ionisation constant of a weak base MOH, is given by the expression + – [M ][OH ] Kb = [MOH] Values of ionisation constant of some weak bases at a particular temperature are given below: Base Dimethylamine Urea Pyridine Ammonia –4 –14 –9 –5 Kb 5.4 × 10 1.3 × 10 1.77 × 10 1.77 × 10 Arrange the bases in decreasing order of the extent of their ionisation at equilibrium. Which of the above base is the strongest?
Show answer
• Order of extent of ionisation at equilibrium is as follows : Dimethylamine > Ammonia > Pyridine > Urea • Since dimethylamine will ionise to the maximum extent it is the strongest base out of the four given bases. – – – –
Q26Short answer
Conjugate acid of a weak base is always stronger. What will be the decreasing order of basic strength of the following conjugate bases? – – – – OH , RO , CH3COO , Cl
Show answer
RO > OH > CH3COO > Cl
Q27Short answer
Arrange the following in increasing order of pH. KNO3 (aq), CH3COONa (aq), NH4Cl (aq), C6H5COONH4 (aq) –4
Show answer
NH4Cl < C6H5COONH4 < KNO3 < CH3COONa
Q28Short answer
The value of Kc for the reaction 2HI (g) H2 (g) + I2 (g) is 1 × 10 At a given time, the composition of reaction mixture is –5 –5 –5 [HI] = 2 × 10 mol, [H2] = 1 × 10 mol and [I2] = 1 × 10 mol In which direction will the reaction proceed? + –8
Show answer
At a given time the reaction quotient Q for the reaction will be given by the expression. [H 2 ][ I 2 ] Q= 2 [HI ] –5 –5 1 × 10 × 1 × 10 1 = –5 2 = (2 × 10 ) 4 –1 = 0.25 = 2.5 × 10 –4 As the value of reaction quotient is greater than the value of Kc i.e. 1× 10 the reaction will proceed in the reverse direction. –8 –3
Q29Short answer
On the basis of the equation pH = – log [H ], the pH of 10 mol dm–3 solution of HCl should be 8. However, it is observed to be less than 7.0. Explain the reason.
Show answer
Concentration of 10 mol dm indicates that the solution is very dilute. Hence, the contribution of H3O+ concentration from water is significant and should also be included for the calculation of pH.
Q30Short answer
pH of a solution of a strong acid is 5.0. What will be the pH of the solution obtained after diluting the given solution a 100 times?
Show answer
(i) pH = 5 + –5 –1 [H ] = 10 mol L On 100 times dilution + –7 –1 [H ] = 10 mol L + On calculating the pH using the equation pH = – log [H ], value of pH comes out to be 7. It is not possible. This indicates that solution is very dilute. Hence, Total hydrogen = [H+] ion concentration ⎡Contribution of ⎤ ⎡Contribution of ⎤ ⎢H O+ ion ⎥ ⎢H O+ ion ⎥ = ⎢concentration ⎥ 3 + ⎢concentration ⎥ ⎢of acid ⎥ ⎢of water ⎥ ⎣ ⎦ ⎣ ⎦ –7 –7 = 10 + 10 . pH = 2 × 10–7 = 7 – log 2 = 7 – 0.3010 = 6.6990 BaSO4 (s) 2–
Q31Short answer
A sparingly soluble salt gets precipitated only when the product of concentration of its ions in the solution (Qsp) becomes greater than its solubility –4 product. If the solubility of BaSO4 in water is 8 × 10 mol dm–3. Calculate its –3 solubility in 0.01 mol dm of H2SO4.
Show answer
Ba2+ (aq) + SO 4 (aq) At t = 0 1 0 0 At equilibrium in water 1–S S S At equilibrium in the presence 1–S S (S+0.01) of sulphuric acid 2– 2 K sp for BaSO4 in water = [Ba2+] [ SO 4 ] = (S) (S) = S But S = 8 × 10–4 mol dm–3 –4 2 –8 ∴ Ksp = (8×10 ) = 64 × 10 ... (1) The expression for Ksp in the presence of sulphuric acid will be as follows : Ksp = (S) (S + 0.01) ... (2) Since value of Ksp will not change in the presence of sulphuric acid, therefore from (1) and (2) –8 (S) (S + 0.01) = 64 × 10 2 –8 S + 0.01 S = 64 × 10 2 –8 S + 0.01 S – 64 × 10 = 0 2 –8 – 0.01 ± (0.01) + (4 × 64 × 10 ) S= –4 –8 – 0.01 ± 10 + (256 × 10 ) = –4 –2 – 0.01 ± 10 (1 + 256 × 10 ) = –2 – 0.01 ± 10 1 + 0.256 = –2 – 0.01 ± 10 1.256 = –2 –2 – 10 + (1.12 × 10 ) = –2 (–1+1.12) × 10 0.12 –2 = = × 10 2 2 –4 = 6 × 10 mol dm–3 99 Equilibrium
Q32Short answer
pH of 0.08 mol dm–3 HOCl solution is 2.85. Calculate its ionisation constant.
Show answer
pH of HOCl = 2.85 + But, – pH = log [H ] + ∴ – 2.85 = log [H ] + 3 .15 = log [H ] + [H ] = 1.413 × 10–3 + For weak mono basic acid [H ] = Ka × C + 2 –3 2 [H ] (1.413 × 10 ) Ka = = C 0.08 –6 –5 = 24.957 × 10 = 2.4957 × 10
Q33Short answer
Calculate the pH of a solution formed by mixing equal volumes of two solutions A and B of a strong acid having pH = 6 and pH = 4 respectively. –11
Show answer
pH of Solution A = 6 + –6 –1 Therefore, concentration of [H ] ion in solution A = 10 mol L pH of Solution B = 4 + –4 –1 Therefore, Concentration of [H ] ion concentration of solution B = 10 mol L On mixing one litre of each solution, total volume = 1L + 1L = 2L + Amount of H ions in 1L of Solution A= Concentration × volume V –6 = 10 mol × 1L + –4 Amount of H ions in 1L of solution B = 10 mol × 1L + ∴ Total amount of H ions in the solution formed by mixing solutions A –6 –4 and B is (10 mol + 10 mol) This amount is present in 2L solution. −4 –4 –4 10 (1 + 0.01) 1.01 × 10 –1 1.01 × 10 –1 ∴ Total [H+] = = mol L = mol L 2 2 2 –4 –1 = 0.5 × 10 mol L –5 –1 = 5 × 10 mol L + pH = – log [H ] = – log (5 × 10–5) = – [log 5 + (– 5 log 10)] = – log 5 + 5 = 5 – log 5 = 5 – 0.6990 = 4.3010 = 4.3
Q34Short answer
The solubility product of Al (OH)3 is 2.7 × 10 . Calculate its solubility in gL–1 and also find out pH of this solution. (Atomic mass of Al = 27 u). 91 Equilibrium
Show answer
Let S be the solubility of Al(OH)3. Al (OH)3 Al 3+ (aq) + 3OH (aq) – Concentration of species at t = 0 1 0 0 Concentration of various species at equilibrium 1–S S 3S 3+ – 3 3 4 Ksp = [Al ] [OH ] = (S) (3S) = 27 S –11 K sp 27 × 10 –12 S = = = 1 × 10 27 27 × 10 –3 –1 S = 1× 10 mol L (i) Solubility of Al(OH)3 Molar mass of Al (OH)3 is 78 g. Therefore, –1 –3 –3 –1 Solubility of Al (OH)3 in g L = 1 × 10 × 78 g L–1 = 78 × 10 g L –2 –1 = 7.8 × 10 g L (ii) pH of the solution –3 –1 S = 1×10 mol L – –3 –3 [OH ] = 3S = 3×1×10 = 3 × 10 pOH = 3 – log 3 pH = 14 – pOH = 11 + log 3 = 11.4771 –8
Q35Short answer
Calculate the volume of water required to dissolve 0.1 g lead (II) chloride to –8 get a saturated solution. (Ksp of PbCl2 = 3.2 × 10 , atomic mass of Pb = 207 u).
Show answer
Ksp of PbCl2 = 3.2 × 10 Let S be the solubility of PbCl2. PbCl2 (s) Pb 2+ – (aq) + 2Cl (aq) Concentration of species at t = 0 1 0 0 Concentration of various species at equilibrium 1–S S 2S 2+ – 2 2 3 Ksp = [Pb ] [Cl ] = (S) (2S) = 4S Ksp = 4S –8 K sp 3.2 × 10 –1 –9 –1 S = = mol L = 8 × 10 mol L 4 4 –1 –3 –1 S = 3 8 × 10 –9 = 2 × 10 –3 mol L ∴ S = 2 × 10 mol L 101 Equilibrium Molar mass of PbCl2 = 278 –3 –1 ∴ Solubility of PbCl2 in g L–1 = 2 × 10 × 278 g L –3 –1 = 556 × 10 g L –1 = 0.556 g L To get saturated solution, 0.556 g of PbCl2 is dissolved in 1 L water. 0.1 0.1 g PbCl2 is dissolved in L = 0.1798 L water. 0.556 To make a saturated solution, dissolution of 0.1 g PbCl2 in 0.1798 L ≈ 0.2 L of water will be required. V V V V
Q36Short answer
A reaction between ammonia and boron trifluoride is given below: : NH3 + BF3 → H3N : BF3 Identify the acid and base in this reaction. Which theory explains it? What is the hybridisation of B and N in the reactants?
Q37Short answer
Following data is given for the reaction: CaCO3 (s) → CaO (s) + CO2 (g) V –1 ∆f H [CaO(s)] = – 635.1 kJ mol V –1 ∆f H [CO2(g)] = – 393.5 kJ mol V –1 ∆f H [CaCO3(s)] = – 1206.9 kJ mol Predict the effect of temperature on the equilibrium constant of the above reaction.
Show answer
∆rH = ∆f H [CaO(s)] + ∆f H [CO2(g)] – ∆f H [CaCO3(s)] V –1 ∴ ∆rH = 178.3 kJ mol The reaction is endothermic. Hence, according to Le-Chatelier’s principle, reaction will proceed in forward direction on increasing temperature. IV. Matching Type
Q38Multiple choice
Match the following equilibria with the corresponding condition (i) Liquid Vapour
- (a)Saturated solution (ii) Solid Liquid
- (b)Boiling point (iii) Solid Vapour
- (c)Sublimation point (iv) Solute (s) Solute (solution)
- (d)Melting point (e) Unsaturated solution
Show answer
(a) Saturated solution (ii) Solid Liquid
(b) Boiling point (iii) Solid Vapour
(d) Melting point (e) Unsaturated solution
(c) Sublimation point (iv) Solute (s) Solute (solution)
Q39Multiple choice
For the reaction : N2 (g) + 3H2(g) 2NH3(g) [NH3 ] Equilibrium constant Kc = 3 [N 2 ][H2 ] Some reactions are written below in Column I and their equilibrium constants in terms of Kc are written in Column II. Match the following reactions with the corresponding equilibrium constant Column I (Reaction) Column II (Equilibrium constant) (i) 2N2(g) + 6H2(g) 4NH3(g)
- (a)2Kc (ii) 2NH3(g) N2(g) + 3H2(g)
- (b)Kc2 1 3 1 (iii) N2(g) + H2(g) NH3(g)
- (c)Kc 2 2
- (d)Kc
Show answer
(a) 2Kc (ii) 2NH3(g) N2(g) + 3H2(g)
(d) Kc
(b) Kc2 1 3 1 (iii) N2(g) + H2(g) NH3(g)
(c) Kc 2 2
Q40Multiple choice
Match standard free energy of the reaction with the corresponding equilibrium constant (i) ∆G >0
- (a)K>1 (ii) ∆G <0
- (b)K=1 (iii) ∆G =0
- (c)K=0
- (d)K<1
Show answer
(a) K>1 (ii) ∆G <0
(d) K<1
(b) K=1 (iii) ∆G =0
(c) K=0
Q41Multiple choice
Match the following species with the corresponding conjugate acid Species Conjugate acid 2– (i) NH3
- (a)CO3 – + (ii) HCO3
- (b)NH4 + (iii) H2O
- (c)H3O – (iv) HSO4
- (d)H2SO4 (e) H2CO3
Show answer
(a) CO3 – + (ii) HCO3
(b) NH4 + (iii) H2O
(c) H3O – (iv) HSO4
(d) H2SO4 (e) H2CO3
Q42Multiple choice
Match the following graphical variation with their description A B (i)
- (a)Variation in product concentration with time (ii)
- (b)Reaction at equilibrium (iii)
- (c)Variation in reactant concentration with time 93 Equilibrium
Show answer
(a) Variation in product concentration with time (ii)
(c) Variation in reactant concentration with time 93 Equilibrium
(b) Reaction at equilibrium (iii)
Q43Multiple choice
Match Column (I) with Column (II). Column I Column II (i) Equilibrium
- (a)∆G > 0, K < 1 (ii) Spontaneous reaction
- (b)∆G = 0 (iii) Non spontaneous reaction
- (c)∆G = 0
- (d)∆G < 0, K > 1
Show answer
(a) ∆G > 0, K < 1 (ii) Spontaneous reaction
(b) ∆G = 0 (iii) Non spontaneous reaction
(c) ∆G = 0
(d) ∆G < 0, K > 1
Q44Assertion & reason
Assertion (A): Increasing order of acidity of hydrogen halides is HF < HCl < HBr < HI
Reason (R): While comparing acids formed by the elements belonging to the same group of periodic table, H–A bond strength is a more important factor in determining acidity of an acid than the polar nature of the bond. (i) Both A and R are true and R is the correct explanation of A. (ii) Both A and R are true but R is not the correct explanation of A. (iii) A is true but R is false. (iv) Both A and R are false.
- (i)Both A and R are true and R is the correct explanation of A.
- (ii)Both A and R are true but R is not the correct explanation of A.
- (iii)A is true but R is false.
- (iv)Both A and R are false.
Show answer
(i) Both A and R are true and R is the correct explanation of A.
Q45Assertion & reason
Assertion (A): A solution containing a mixture of acetic acid and sodium acetate maintains a constant value of pH on addition of small amounts of acid or alkali.
Reason (R): A solution containing a mixture of acetic acid and sodium acetate acts as a buffer solution around pH 4.75. (i) Both A and R are true and R is correct explanation of A. (ii) Both A and R are true but R is not the correct explanation of A. (iii) A is true but R is false. (iv) Both A and R are false.
- (i)Both A and R are true and R is correct explanation of A.
- (ii)Both A and R are true but R is not the correct explanation of A.
- (iii)A is true but R is false.
- (iv)Both A and R are false.
Show answer
(i) Both A and R are true and R is correct explanation of A.
Q46Assertion & reason
Assertion (A): The ionisation of hydrogen sulphide in water is low in the presence of hydrochloric acid.
Reason (R): Hydrogen sulphide is a weak acid. (i) Both A and R are true and R is correct explanation of A. (ii) Both A and R are true but R is not correct explanation of A. (iii) A is true but R is false (iv) Both A and R are false
- (i)Both A and R are true and R is correct explanation of A.
- (ii)Both A and R are true but R is not correct explanation of A.
- (iii)A is true but R is false
- (iv)Both A and R are false
Show answer
(ii) Both A and R are true but R is not correct explanation of A.
(iii) A is true but R is false
Q47Assertion & reason
Assertion (A): For any chemical reaction at a particular temperature, the equilibrium constant is fixed and is a characteristic property.
Reason (R): Equilibrium constant is independent of temperature. (i) Both A and R are true and R is correct explanation of A. (ii) Both A and R are true but R is not correct explanation of A. (iii) A is true but R is false. (iv) Both A and R are false.
- (i)Both A and R are true and R is correct explanation of A.
- (ii)Both A and R are true but R is not correct explanation of A.
- (iii)A is true but R is false.
- (iv)Both A and R are false.
Q48Assertion & reason
Assertion (A): Aqueous solution of ammonium carbonate is basic.
Reason (R): Acidic/basic nature of a salt solution of a salt of weak acid and weak base depends on Ka and Kb value of the acid and the base forming it. (i) Both A and R are true and R is correct explanation of A. (ii) Both A and R are true but R is not correct explanation of A. (iii) A is true but R is false. (iv) Both A and R are false.
- (i)Both A and R are true and R is correct explanation of A.
- (ii)Both A and R are true but R is not correct explanation of A.
- (iii)A is true but R is false.
- (iv)Both A and R are false.
Show answer
(i) Both A and R are true and R is correct explanation of A.
Q49Assertion & reason
Assertion (A): An aqueous solution of ammonium acetate can act as a buffer.
Reason (R): Acetic acid is a weak acid and NH4OH is a weak base. (i) Both A and R are true and R is correct explanation of A. (ii) Both A and R are true but R is not correct explanation of A. (iii) A is false but R is true. (iv) Both A and R are false.
- (i)Both A and R are true and R is correct explanation of A.
- (ii)Both A and R are true but R is not correct explanation of A.
- (iii)A is false but R is true.
- (iv)Both A and R are false.
Show answer
(iii) A is false but R is true.
Q50Assertion & reason
Assertion (A): In the dissociation of PCl 5 at constant pressure and temperature addition of helium at equilibrium increases the dissociation of PCl5 .
Reason (R): Helium removes Cl2 from the field of action. (i) Both A and R are true and R is correct explanation of A. (ii) Both A and R are true but R is not correct explanation of A. (iii) A is true but R is false. (iv) Both A and R are false.
- (i)Both A and R are true and R is correct explanation of A.
- (ii)Both A and R are true but R is not correct explanation of A.
- (iii)A is true but R is false.
- (iv)Both A and R are false.
Show answer
(iv) Both A and R are false.
Q51Multiple choice
How can you predict the following stages of a reaction by comparing the value of Kc and Qc?
- (i)Net reaction proceeds in the forward direction. 95 Equilibrium
- (ii)Net reaction proceeds in the backward direction.
- (iii)No net reaction occurs.
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(i) Net reaction proceeds in the forward direction. 95 Equilibrium
(ii) Net reaction proceeds in the backward direction.
(iii) No net reaction occurs.
Hint: Hint : A x B y x A (aq) + y B (aq) p+ q− p+ q–
Q52Long answer
On the basis of Le Chatelier principle explain how temperature and pressure can be adjusted to increase the yield of ammonia in the following reaction. N2(g) + 3H2(g) 2NH3(g) ∆ H = – 92.38 kJ mol–1 What will be the effect of addition of argon to the above reaction mixture at constant volume? p+ q−
Q53Long answer
A sparingly soluble salt having general formula A x B y and molar solubility S is in equilibrium with its saturated solution. Derive a relationship between the solubility and solubility product for such salt.
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p+ q– S moles of AxBy dissolve to give x S moles of A and y S moles of B .]
Q54Multiple choice
Write a relation between ∆G and Q and define the meaning of each term and answer the following :
- (a)Why a reaction proceeds forward when Q < K and no net reaction occurs when Q = K.
- (b)Explain the effect of increase in pressure in terms of reaction quotient Q. for the reaction : CO (g) + 3H2 (g) CH4 (g) + H2O (g)
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∆G = ∆G + RT lnQ ∆G = Change in free energy as the reaction proceeds ∆G = Standard free energy change Q = Reaction quotient R = Gas constant T = Absolute temperature Since ∆G = – RT lnK ∴ ∆G = – RT lnK + RT lnQ = RT ln K If Q < K, ∆G will be negative. Reaction proceeds in the forward direction. If Q = K, ∆G = 0, no net reaction. [Hint: Next relate Q with concentration of CO, H2, CH4 and H2O in view of reduced volume (increased pressure). Show that Q < K and hence the reaction proceeds in forward direction.] 103 Equilibrium