Chemical Equilibrium PYQs Set 2 (PDF)

Set 2 of 5 · Questions 31-60 of 138

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Mere Teacher · Previous Year Questions JEE Main Chemistry · Chemical Equilibrium · Set 2 (Q31-60)
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31. $0.023 g of sodium metal is reacted with 100 cm^{3} of water. The pH of the resulting solution is$ (1) $10$ (2) $11$ (3) $9$ (4) $12$ 32. $One dm^{3} solution containing 10^{- 5} moles each of Cl^{-} ions and CrO_{4}^{2 -} ions is treated with 10^{- 4} moles of silver nitrate. Which one of the following observations is made? (K_{sp} Ag_{2} CrO_{4} = 4 \times 10^{- 12}), (K_{sp} AgCl = 1 \times 10^{- 10})$ (1) $Precipitation does not occur.$ (2) $Silver chromate gets precipitated first.$ (3) $Silver chloride gets precipitated first.$ (4) $Both silver chromate and silver chloride start precipitating simultaneously$ 33. $pH value of which one of the following is not equal to one?$ (1) $0.1 M HNO_{3}$ (2) $0.1 M CH_{3} COOH$ (3) $0.05 M H_{2} SO_{4}$ (4) $50 cm^{3} of 0.4 MHCl + 50 cm^{3} of 0.2 M NaOH$ 34. $N_{2} + 3 H_{2} ⇌ 2 NH_{3} + heat. What is the effect of the increase of temperature on the equilibrium of the reaction?$ (1) $Equilibrium is unaltered.$ (2) $Reaction rate does not change.$ (3) $Equilibrium is shifted to the left.$ (4) $Equilibrium is shifted to the right.$ 35. $For the equilibrium, CaCO_{3 (s)} ⇌ CaO_{(s)} + CO_{2 (g)}; K_{p} = 1.64 atm at 1000 K 50 g of CaCO_{3} in a 10 litre closed vessel is heated to 1000 K . Percentage of CaCO_{3} that remains unreacted at equilibrium is (Given : R = 0.082 L atm K^{- 1} mol^{- 1})$ (1) $40$ (2) $50$ (3) $60$ (4) $20$ 36. $10^{- 6} MNaOH is diluted 100 times. The pH of the diluted base is$ (1) $between 5 and 6$ (2) $between 6 and 7$ (3) $between 10 and 11$ (4) $between 7 and 8$ 37. $K_{a} values for acids H_{2} SO_{3}, HNO_{2}, CH_{3} COOH and HCN are respectively 1.3 \times 10^{- 2}, 4 \times 10^{- 4}, 1.8 \times 10^{- 5} and 4 \times 10^{- 10}, which of the above acids produce stronger conjugate base in aqueous solution?$ (1) $H_{2} SO_{3}$ (2) $HNO_{2}$ (3) $CH_{3} COOH$ (4) $HCN$ 38. $Consider the following reaction : N_{2} O_{4} (g) ⇌ 2 NO_{2} (g); Δ H^{0} = + 58 kJ For each of the following cases (a, b), the direction in which the equilibrium shifts is:(A) Temperature is decreased (B) Pressure is increased by adding N_{2} at constantT.$ (1) $(A) Towards product, (B) towards reactant$ (2) $(A) Towards reactant, (B) no change$ (3) $(A) Towards reactant, (B) towards product$ (4) $(A) Towards product, (B) no change$ 39. $The value of K_{c} is 64 at 800 K for the reaction N_{2} (g) + 3 H_{2} (g) ⇌ 2 NH_{3} (g) The value of K_{c} for the following reaction is NH_{3} (g) ⇌ \frac{1}{2} N_{2} (g) + \frac{3}{2} H_{2} (g)$ (1) $1/8$ (2) $1/64$ (3) $8$ (4) $1/4$ 40. $Which among the following has highest pH ?$ (1) $1 M H_{2} SO_{4}$ (2) $0.1 M NaOH$ (3) $1 M HCl$ (4) $1 M NaOH$ 41. $For the reaction, 2 SO_{2} (g) + O_{2} (g) ⇌ 2 SO_{3} (g), Δ H = - 57.2 kJ mol^{- 1} and K_{c} = 1.7 \times 10^{16} Which of the following statement is Incorrect?$ (1) $The equilibrium constant is large suggestive of reaction going to completion and so no catalyst is required.$ (2) $The equilibrium will shift in forward direction as the pressure increases.$ (3) $The equilibrium constant decreases as the temperature increases$ (4) $The addition of inert gas at constant volume will not affect the equilibrium constant.$ 42. $A buffer solution contains 0.1 mole of sodium acetate in 1000 cm^{3} of 0.1 M acetic acid. To the above buffer solution, 0.1 mole of sodium acetate is further added and dissolved. The pH of the resulting buffer is equal to$ (1) $p K_{a} - log 2$ (2) $p K_{a}$ (3) $p K_{a} + 2$ (4) $p K_{a} + log 2$ 43. $For the reaction Fe_{2} N (s) + \frac{3}{2} H_{2} (g) ⇌ 2 Fe (s) + NH_{3} (g)$ (1) $K_{C} = K_{p} (RT)^{1/2}$ (2) $K_{C} = K_{p} (RT)$ (3) $K_{C} = K_{p} (RT)^{3/2}$ (4) $K_{C} = K_{p} (RT)^{- 1/2}$ 44. $Which of the following is the strongest base?$ (1) $Cl^{-}$ (2) $OH^{-}$ (3) $CH_{3} O^{-}$ (4) $CH_{3} COO^{-}$ 45. $The yield of the products in the reaction, A_{2 (g)} + 2 B_{(g)} ⇌ C_{(g)} + Q kJ would be higher at$ (1) $high temperature and high pressure$ (2) $high temperature and low pressure$ (3) $low temperature and high pressure$ (4) $low temperature and low pressure.$ 46. $Solubility product of a salt AB is 1 \times 10^{- 8} M^{2} in a solution in which the concentration of A^{+} ions is 10^{- 3} M . The salt will precipitate when the concentration of B^{-} ions is kept$ (1) $between 10^{- 8} M to 10^{- 7} M$ (2) $between 10^{- 7} M to 10^{- 8} M$ (3) $> 10^{- 5} M$ (4) $< 10^{- 8} M .$ 47. $The reaction quotient, ' Q_{c}' is useful in predicting the direction of the reaction. Which of the following is incorrect?$ (1) $If Q_{c} > K_{c}, the reverse reaction is favoured.$ (2) $If Q_{c} < K_{c}, the forward reaction is favoured.$ (3) $If Q_{c} > K_{c}, forward reaction is favoured.$ (4) $If Q_{c} = K_{c}, no reaction occur.$ 48. $Consider the general reaction given below at 400 K x A (g) ⇌ y B (g) The values of K_{p} and K_{c} are studied under the same condition of temperature but variation in x and y . (i) K_{p} = 85.87 and K_{c} = 2.586 appropriate units (ii) K_{p} = 0.862 and K_{c} = 28.62 appropriate units. The values of x and y in (i) and (ii) respectively are: (i) (ii)$ (1) $1,3 2,1$ (2) $4,1 4,1$ (3) $3,1 3,1$ (4) $1,2 2,1$ 49. $Equilibrium constants K_{1} and K_{2} for the following equilibria (1) NO_{(g)} + \frac{1}{2} O_{2 (g)} ⇌ NO_{2 (g)} (2) 2 NO_{2 (g)} ⇌ 2 NO_{(g)} + O_{2 (g)} are related as :$ (1) $K_{1} = K_{2}$ (2) $K_{2} = \frac{1}{K _{1}}$ (3) $K_{1} = 2 K_{2}$ (4) $K_{2} = \frac{1}{K _{1}^{2}}$ 50. $Consider the following reversible chemical reactions: A_{2} (g) + B_{2} (g) ⇌ K_{1} (K_{1}) 2 AB (g) \dots \dots (1) 6 AB (g) ⇌ K_{2} 3 A_{2} (g) + 3 B_{2} (g) \dots .. (2) The relation between K_{1} and K_{2} is:$ (1) $K_{1} K_{2} = \frac{1}{3}$ (2) $K_{2} = K_{1} 3$ (3) $K_{2} = K_{1}^{- 3}$ (4) $K_{1} K_{2} = 3$ 51. $For independent process at 300 K. Process ∆ H / k J m o l^{- 1} ∆ S / J K^{- 1} A -25 -80 B -22 40 C 25 -50 D 2220 The number of non-spontaneous process from the following is_______.$ 52. $For the reaction N_{2} O_{4} (g) ⇌ 2 NO_{2} (g), K_{p} = 0.492 atm at 300 K . K_{c} for the reaction at same temperature is_______\times 10^{- 2} . (Given : R = 0.082 L atm mol^{- 1} K^{- 1})$ 53. $For the reaction: C_{2} H_{6} \to C_{2} H_{4} + H_{2} the reaction enthalpy ∆_{r} H^{0 =}____ kJ mol^{- 1} (Round off to the Nearest Integer). [Given : Bond enthalpies in kJ mol^{- 1} : C - C : 347, C = C : 611; C - H : 414, H - H : 436]$ 54. $The average S-F bond energy in k J mo l^{- 1} of SF_{6} is ____ (Rounded off to the nearest integer) [Given : The values of standard enthalpy of formation of SF_{6} (g), S (g) and F (g) are -1100,275 and 80 k J mo l^{- 1} respectively.]$ 55. $The gas phase reaction 2 A (g) ⇌ A_{2} (g) at400 K has ∆ G ° = + 25.2 kJ mol^{- 1} . The equilibrium constant K_{C} for this reaction is_________\times 10^{- 2} . (Round off to the Nearest integer) Use: R = 8.3 J mol^{- 1} K^{- 1}, ln 10 = 2.3 log_{10} 2 = 0.3, 1 atm = 1 bar] [antilog (-0.3)=0.501]$ 56. $For a reaction X + Y = 2 Z, 1.0 mol of X, 1.5 mol of Y and 0.5 mol of Z were taken in a 1 L vessel and allowed to react. At equilibrium, the concentration of Z was 1.0 mol L^{- 1} . The equilibrium constant of the reaction is \frac{x}{15} . The value of x is$ 57. $At 25°C, the enthalpy of the following processes are given: H_{2} (g) + O_{2} (g) \to 2OH(g) ∆ H° = 78kJ m o l^{- 1} H_{2} (g) +^{l} /_{2} O_{2} (g) \to H_{2} O(g) ∆ H° = -242 kJ m o l^{- 1} H_{2} (g) \to 2H(g) ∆ H° = 436 kJ m o l^{- 1} ½ O_{2} (g) \to O(g) ∆ H° = 249 k J m o l^{- 1} What would be the value of X for the following reaction?_____(Nearest integer) H_{2} O(g) \to H(g) + OH(g) ∆ H° = X kJ m o l^{- 1}$ 58. $Consider the following equation : 2 S O_{2} (g) + O_{2} (g) ⇌ 2 S O_{3} (g), ∆ H = -190 kJ The number of factors which will increase the yield of S O_{3} at equilibrium from the following is A. Increasing temperature B. Increasing pressure C Adding more S O_{2} D. Adding more O_{2} E. Addition of catalyst$ 59. $The standard enthalpies of formation of Al_{2} O_{3} and CaO are - 1675 kJ mol^{- 1} and - 635 kJ mol^{- 1} respectively. For the reaction 3 CaO + 2 Al \to 3 Ca + A l_{2} O_{3} the standard reaction enthalpy ∆_{r} H^{0 =}____ Kj.(Round off to the Nearest Integer).$ 60. $For the reaction A (g) ⇌ B (g) at 495 K. ∆_{r} G ° = - 9.478 kJ mol^{- 1} If we start the reaction in a closed container at 495 K with 22 millimoles of A,the amount of B is the equilibrium mixture is....millimoles. (Round off to theNearest Integer). (R = 8.314 J mol^{- 1} K^{- 1}; l n 10 = 2.303)$