Chemical Equilibrium PYQs Set 1 (PDF)

Set 1 of 5 · Questions 1-30 of 138

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Mere Teacher · Previous Year Questions JEE Main Chemistry · Chemical Equilibrium · Set 1 (Q1-30)
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1. $In which one of the following equilibria, K_{p} \neq = K_{c} ?$ (1) $2 C (s) + O_{2} (g) ⇌ 2 CO (g)$ (2) $2 HI (g) ⇌ H_{2} (g) + I_{2} (g)$ (3) $NO_{2} (g) + SO_{2} (g) ⇌ NO (g) + SO_{3} (g)$ (4) $2 NO (g) ⇌ N_{2} (g) + O_{2} (g)$ 2. $A vessel at 1000 K contains CO_{2} with a pressure of 0.5 atm. Some of CO_{2} is converted into CO on addition of graphite. If total pressure at equilibrium is 0.8 atm, then Kp is:$ (1) $1.8 atm$ (2) $0.3 atm$ (3) $3 atm$ (4) $0.18 atm$ 3. $H_{2} S is passed into one dm^{3} of a solution containing 0.1 mole of Zn^{2 +} and 0.01 mole of Cu^{2 +} till the sulphide ion concentration reaches 8.1 \times 10^{- 19} moles. Which one of the following statements is true? [K_{sp} of ZnS and CuS are 3 \times 10^{- 22} and 8 \times 10^{- 36} respectively]$ (1) $Only ZnS precipitates$ (2) $Both CuS and ZnS precipitate$ (3) $Only CuS precipitates$ (4) $No precipitation occurs$ 4. $The gas phase reaction 2 N O_{2} (g) ® N_{2} O_{4} (g) is an exothermic reaction. The decomposition of N_{2} O_{4}, in equilibrium mixture of N O_{2} (g) and N_{2} O_{4} (g), can be increased by:$ (1) $addition of an inert gas at constant pressure.$ (2) $lowering the temperature$ (3) $increasing the pressure$ (4) $addition of an inert gas at constant volume.$ 5. $2 HI_{(g)} ⇌ H_{2 (g)} + I_{2 (g)} The equilibrium constant of the above reaction is 6.4 at 300 K . If 0.25 mole each of H_{2} and I_{2} are added to the system, the equilibrium constant will be$ (1) $0.8$ (2) $3.2$ (3) $1.6$ (4) $6.4$ 6. $Consider the reaction X_{2} Y (g) = X_{2} (g) + \frac{1}{2} Y_{2} (g) The equation representing correct relationship between the degree of dissociation (x) of X_{2} Y (g) with its equilibrium constant Kp is . Assume x to be very very small.$ (1) $x = 3 \frac{2 Kp}{p}$ (2) $x = 3 \frac{2 Kp ^{2}}{p}$ (3) $x = 3 \frac{Kp}{p}$ (4) $x = 3 \frac{K p}{2 p}$ 7. $The pH of 10^{- 8} MHCl solution is$ (1) $8$ (2) $more than 8$ (3) $between 6 and 7$ (4) $slightly more than 7.$ 8. $Which of the following salts on being dissolved in water gives pH > 7 at 25^{\circ} C ?$ (1) $KCN$ (2) $KNO_{3}$ (3) $NH_{4} Cl$ (4) $NH_{4} CN$ 9. $In the reaction, Fe (OH)_{3 (s)} ⇌ Fe^{3 +}_{(aq)} + 3 OH^{-}_{(aq),} if the concentration of OH^{-} ions is decreased by 1/4 times, then the equilibrium concentration of Fe^{3 +} will increase by$ (1) $8 times$ (2) $16 times$ (3) $64 times$ (4) $4 times.$ 10. $The equilibrium constant for the reaction, N_{2 (g)} + O_{2 (g)} ⇌ 2 NO_{(g)} is 4 \times 10^{- 4} at 2000 K . In presence of a catalyst, the equilibrium is attained ten times faster. Therefore, the equilibrium constant in presence of catalyst at 2000 K is$ (1) $4 \times 10^{- 3}$ (2) $40 \times 10^{- 4}$ (3) $4 \times 10^{- 4}$ (4) $4 \times 10^{- 2}$ 11. $5.1 g NH_{4} SH is introduced in 3.0 L evacuated flask at 327° C, 30 % of the solid NH_{4} SH decomposed to NH_{3} and H_{2} as gases. The K_{p} of the reaction at 327° C is (R = 0.082 L mol^{- 1}, molar mass of S = 32 g mol^{- 1}, molar massof (N = 14 g mol^{- 1})$ (1) $0.242 \times 10^{- 4} atm^{2}$ (2) $1 \times 10^{- 4} atm^{2}$ (3) $4.9 \times 10^{- 3} atm^{2}$ (4) $0.242 atm^{2}$ 12. $Solubility of AgCl is least in$ (1) $0.1 M NaCl$ (2) $pure water$ (3) $0.1 M BaCl_{2}$ (4) $0.1 M AlCl_{3}$ 13. $The equilibrium constant for the reaction SO_{3} (g) ⇌ SO_{2} (g) + \frac{1}{2} O_{2} (g) is K_{c} = 4.9 \times 10^{- 2} . The value of K_{c} for the reaction given below is 2 SO_{2} (g) + O_{2} (g) ⇌ 2 SO_{3} (g) is :$ (1) $4.9$ (2) $49$ (3) $41.6$ (4) $416$ 14. $In the following system, PCl_{5} (g) ⇋ PCl_{3} (g) + Cl_{2} (g) at equilibrium, upon addition of xenon gas at constant T ∖ & p, the concentration of$ (1) $PCl_{5}, PCl_{3} & Cl_{2} remain constant$ (2) $PCl_{3} will increase$ (3) $Cl_{2} will decrease$ (4) $PCl_{5} will increase$ 15. $On adding which of the following, the pH of 20 mL of 0.1 NHCl will not alter?$ (1) $1 mL of 1 NHCl$ (2) $20 mL of distilled water$ (3) $1 mL of 0.1 NNaOH$ (4) $500 mL of HCl of pH = 1$ 16. $Two solids dissociate as follows A (s) \to B (g) + C (g); K_{P_{1}} = x atm^{2} D (s) \to C (g) + E (g); K_{P_{2}} = y atm^{2} The total pressure when both the solids dissociate simultaneously is:$ (1) $x + y atm$ (2) $2 x + y atm$ (3) $(x + y) atm$ (4) $x^{2} + y^{2} atm$ 17. $Consider the following chemical equilibrium of the gas phase reaction at a constant temperature: A (g) ⇌ B (g) + C (g) If p being the total pressure, K_{p} is the pressure equilibrium constant and α is the degree of dissociation, then which of the following is true at equilibrium?$ (1) $If K_{p} value is extremely high compared to p, α becomes much less than unity$ (2) $When p increase α increases$ (3) $If p value is extremely high compared to K_{p}, α \approx 1$ (4) $When p increases α decreases$ 18. $A_{(g)} ⇌ B_{(g)} + \frac{C}{2} (g) The correct relationship between K_{P}, α and equilibrium pressure P is$ (1) $K_{P} = \frac{α ^{1/2} P ^{1/2}}{( 2 + α ) ^{1/2}}$ (2) $K_{P} = \frac{α ^{3/2} P ^{1/2}}{( 2 + α ) ^{1/2} ( 1 - α )}$ (3) $K_{P} = \frac{α ^{1/2} P ^{3/2}}{( 2 + α ) ^{3/2}}$ (4) $K_{P} = \frac{α ^{1/2} P ^{1/2}}{( 2 + α ) ^{3/2}}$ 19. $For the following reactions, equilibrium constants are given: S (s) + O_{2} (g) ⇌ SO_{2} (g); K_{1} = 10^{52} 2 S (s) + 3 O_{2} (g) ⇌ 2 SO_{3} (g); K_{2} = 10^{129} The equilibrium constant for the reaction, 2 SO_{2} (g) + O_{2} (g) ⇌ 2 SO_{3} (g) is:$ (1) $10^{154}$ (2) $10^{181}$ (3) $10^{25}$ (4) $10^{77}$ 20. $The conjugate base of NH_{3} is$ (1) $NH_{4} OH$ (2) $NH_{2} OH$ (3) $NH_{2}^{-}$ (4) $NH_{4}^{+}$ 21. $For the reaction, H_{2} (g) + I_{2} (g) ⇌ 2 HI (g) Attainment of equillibrium is predicted correctly by :$ (1) (2) (3) (4) 22. $When two reactants, A & B are mixed to give products C & D, the reaction quotient Q, at the initial stages of the reaction.$ (1) $is zero$ (2) $decrease with time$ (3) $is independent of time$ (4) $increases with time$ 23. $Which one of the following condition will increase the voltage of the cell represented by the equation : Cu_{(s)} + 2 Ag_{(aq)}^{+} ⇌ Cu^{2 +}_{(aq)} + 2 Ag_{(s)}$ (1) $increase in the dimension of Cu electrode$ (2) $increase in the dimension of Ag electrode$ (3) $increase in the concentration of Cu^{2 +} ions$ (4) $increase in the concentration of Ag^{+} ions.$ 24. $30 cc of \frac{M}{3} HCl, 20 cc of \frac{M}{2} HNO_{3} and 40 cc of \frac{M}{4} NaOH solutions are mixed and the volume was made up to 1 dm^{3} . The pH of the resulting solution is$ (1) $2$ (2) $1$ (3) $3$ (4) $8$ 25. $The pair of compound which cannot exist together in solution is$ (1) $NaHCO_{3} and H_{2} O$ (2) $Na_{2} CO_{3} and NaOH$ (3) $NaHCO_{3} and NaOH$ (4) $NaHCO_{3} and Na_{2} CO_{3}$ 26. $For the reaction, 2 HI_{(g)} ⇌ H_{2 (g)} + I_{2 (g)} - QkJ, the equilibrium constant depends upon$ (1) $catalyst$ (2) $volume$ (3) $temperature$ (4) $pressure$ 27. $At - 20^{\circ} C and 1 atm pressure, a cylinder is filled with equal number of H_{2}, I_{2} and HI molecules for the reaction H_{2} (g) + I_{2} (g) ⇌ 2 HI (g), the K_{p} for the process is x \times 10^{- 1} . x =_____[Given : R = 0.082 L atm K^{- 1} mol^{- 1}]$ (1) $0.01$ (2) $10$ (3) $2$ (4) $1$ 28. $Consider the reaction N_{2} O_{4} (g) ⇌ 2 N O_{2} (g) . The temperature at which K_{C} = 20.4 and K_{p} = 600.1, is _____ K. (Round off to the Nearest Integer) [Assume all gases are ideal and R = 0.0831 L bar K^{- 1} mo l^{- 1}]$ 29. $The ionization enthalpy of Na^{+} formation from N a_{(g)} is 495.8 k J mo l^{- 1}, while the electron gain enthalpy of Br is - 325.0 k J mo l^{- 1} . Given the lattice enthalpy ofNaBris - 728.4 k J mo l^{- 1} . The energy for theformation of NaBr ionic solid is (-) ____\times 10^{- 1} k J mo l^{- 1}$ 30. $For the reaction A_{(g)} \to B_{(g)}, the value of the equilibrium constant at 300 K and 1 atm is equal to 100.0. The value of ∆_{r} G for the reaction at 300 K and 1 atm in J mo l^{- 1} is - xR, where x is ____ (Rounded off to thenearest integer) (R = 8.31 J mo l^{- 1} K^{- 1} and ln 10 = 2.3)$