Chemical Equilibrium PYQs Set 5 (PDF)

Set 5 of 5 · Questions 121-138 of 138

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Mere Teacher · Previous Year Questions JEE Main Chemistry · Chemical Equilibrium · Set 5 (Q121-138)
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121. $For the equilibrium A ⇌ B, the variation of the rate of the forward (a) and reverse (b) reaction with time is given by$ (1) (2) (3) (4) 122. $For the reaction, N_{2} O_{4} ⇌ 2 NO_{2}, graph is plotted as shown below. Identify correct statements.(A) Standard free energy change for the reaction is - 5.40 kJ mol^{- 1} .(B) As ΔG⊖ in graph is positive, N2O4 will not dissociate into NO2 at all.(C) Reverse reaction will go to completion.(D) When 1 mole of N2O4 changes into equilibrium mixture, value of Δ G^{⊖} = - 0.84 kJ mol^{- 1} (E) When 2 mole of NO2 changes into equilibrium mixture, ΔG⊖ for equilibrium mixture is - 6.24 kJ mol^{- 1} . Choose the correct answer from the options given below:$ (1) $(D) and (E) only$ (2) $(A) and (D) only$ (3) $(B) and (C) only$ (4) $(C) and (E) only$ 123. $The equilibrium Cr_{2} O_{7}^{2 -} ⇌ 2 CrO_{4}^{2 -} is shifted to the right in :$ (1) $an acidic medium$ (2) $a basic medium$ (3) $a neutral medium$ (4) $a weakly acidic medium$ 124. $At 500 K, for a reversible reaction A_{2_{(g)}} + B_{2_{(g)}} ⇌ 2 A B_{(g)} in a closed container, K_{c} = 2 \times 10^{- 5} . In the presence of catalyst, the equilibrium is attaining 10 times faster. The equilibrium constant K_{c} in the presence of catalyst at the same temperature is$ (1) $2 \times 10^{- 4}$ (2) $2 \times 10^{- 6}$ (3) $2 \times 10^{- 10}$ (4) $2 \times 10^{- 5}$ 125. $Conjugate base of H_{2} PO_{4}^{-} is$ (1) $HPO_{4}^{-}$ (2) $HPO_{4}^{2 -}$ (3) $H_{3} PO_{4}$ (4) $PO_{4}^{3 -}$ 126. $The following reaction occurs in the Blast furnance where iron ore is reduced to iron metal Fe_{2} O_{3 (s)} + 3 CO_{(g)} ⇌ Fe_{(l)} + 3 CO_{2 (g)} Using the Le-chatelier's principle, predict which one of the following will not disturb the equilibrium.$ (1) $Addition of CO_{2}$ (2) $Removal of CO_{2}$ (3) $Addition of Fe_{2} O_{3}$ (4) $Removal of CO$ 127. $An example for a neutral buffer is$ (1) $ammonium hydroxide and ammonium chloride$ (2) $acetic acid and sodium acetate$ (3) $acetic acid and ammonium hydroxide$ (4) $citric acid and sodium citrate.$ 128. $At 300 K, a gaseous reaction, A \to B + C was found to follow first order kinetics. Starting with pure A, the total pressure at the end of 20 minutes was 100 mm of Hg . The total pressure after the completion of the reaction is 180 mm of Hg . The partial pressure of A (in mm of Hg) is$ (1) $100$ (2) $90$ (3) $180$ (4) $80$ 129. $At a certain temperature, only 50% HI is dissociated into H_{2} and I_{2} at equilibrium. The equilibrium constant is:$ (1) $1.0$ (2) $3.0$ (3) $0.5$ (4) $0.25$ 130. $2 moles of N_{2} O_{4 (g)} is kept in a closed container at 298 K and under 1 atm pressure. It is heated to 596 K when 20 % by mass of N_{2} O_{4 (g)} decomposes to NO_{2} . The resulting pressure is$ (1) $2.4 atm$ (2) $1.2 atm$ (3) $4.8 atm$ (4) $2.8 atm$ 131. $What happens when an inert gas is added to an equilibrium keeping volume unchanged?$ (1) $More product will form$ (2) $Less product will form$ (3) $More reactant will form$ (4) $Equilibrium will remain unchanged$ 132. $Three moles of PCl_{5}, three moles of PCl_{3} and two moles of Cl_{2} are taken in a closed vessel. If at equilibrium the vessel has 1.5 moles of PCl_{5}, the number of moles of PCl_{3} present in it is$ (1) $6$ (2) $4.5$ (3) $5$ (4) $3$ 133. $The equilibrium constant for the reaction A (s) ⇌ M (s) + \frac{1}{2} O_{2} (g) is K_{P} = 4 . At equilibrium, the partial pressure of O_{2} is atm. (Round off to the nearest integer)$ 134. $For the reaction A + B ⇌ 2 C the value of equilibrium constant is 100 at 298K. If the initial concentration of all the three species is 1M each, then the equilibrium concentration of C is x \times 1 0^{- 1} M . The value of x is (Nearest integer)$ 135. $Value of K_{P} for the equilibrium reaction N_{2} O_{4} (g) ⇌ 2 N O_{2} (g) at 288K is 47.9. The K_{C} for this reaction at same temperature is _____ (Nearest integer) (R = 0.083 L bar K^{- 1} mol^{- 1})$ 136. $PC l_{5} dissociates as PC l_{5} (g) ⇌ PC l_{3} (g) + C l_{2} (g) . 5 moles of PC l_{5} are placed in a 200 litre vessel which contains 2 moles of N_{2} and is maintained at 600 K. The equilibrium pressure is 2.46 atm. The equilibrium constant K_{p} for the dissociation of PC l_{5} is _____\times 1 0^{- 3} . (nearest integer) (Given: R = 0.082 L atm K^{- 1} mo l^{- 1}; assume ideal gas behavior)$ 137. $A box contains 0.90 g of liquid water in equilibrium with water vapour at 27°C. The equilibrium vapour pressure of water at 27°C 32.0 Torr. When the volume of the box is increased, some of the liquid water evaporates to maintain the equilibrium pressure. If all the liquid water evaporates, then the volume of the box must be____ litre, [nearest integer](Given: R = 0.082 L atm K^{- 1} m o l^{- 1})(Ignore the volume of the liquid water and assume water vapours behave as an ideal gas.)$ 138. $The O H^{-} concentration in a mixture of 5.0mL of 0.0504M N H_{4} Cl and 2mL of 0.0210 M N H_{3} solution is x \times 1 0^{- 6} M . The value of x is ____. (Nearest integer) [Given K_{w} = 1 \times 1 0^{- 14} and K_{b} = 1.8 \times 1 0^{- 5}]$