Electrochemistry PYQs Set 8 (PDF)

Set 8 of 10 · Questions 211-240 of 293

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Mere Teacher · Previous Year Questions NEET Chemistry · Electrochemistry · Set 8 (Q211-240)
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211. $The standard e.m.f of a galvanic cell involving cell reaction with n = 2 is found to be 0.295 V at 2 5^{o} C. The equilibrium constant of the reaction would be () Given (F = 96500 Cmol^{- 1}, R = 8.314 JK^{- 1} mol^{- 1})$ (1) $2.0 \times 1 0^{11}$ (2) $4.0 \times 1 0^{12}$ (3) $1.0 \times 1 0^{2}$ (4) $1.0 \times 10^{10}$ 212. $The Gibb’s energy for the decomposition of A l_{2} O_{3} at 500 C is as follows \frac{2}{3} A l_{2} O_{3} \to \frac{4}{3} A l + O_{2}, ∆_{r} G = + 960 k J m o l^{- 1} The potential difference needed for the electrolytic reduction of aluminium oxide at 50 0^{o} C is at least$ (1) $4.5 V$ (2) $3.0 V$ (3) $2.5 V$ (4) $5.0 V$ 213. $The E_{M^{3 +} / M^{2 +}}^{0} values for Cr, Mn, Fe and Co are - 0.41, + 1.57, + 0.77 and + 1.97 V respectively. For which one of these metals, the change in oxidation state from +2 to +3 is easiest$ (1) $Cr$ (2) $Mn$ (3) $Fe$ (4) $Co$ 214. $The variation of molar conductivity with concentration of an electrolyte (X) in aqueous solution is shown in figure. The electrolyte X is$ (1) $NaCl$ (2) $HCl$ (3) $CH_{3} COOH$ (4) $KNO_{3}$ 215. $The E^{\circ} of Ce^{4 +} / Ce^{3 +} = 1.6 V Fe^{3 +} / Fe^{2 +} = 0.76 V the E^{\circ} of Fe^{3 +} oxidising Ce^{3 +} is$ (1) $+ 0.84 V$ (2) $- 0.84 V$ (3) $- 2.32 V$ (4) $+ 1.5 V$ 216. $The molar conductivity of a 0.5 m o l / d m^{3} solution of A g N O_{3} with electrolytic conductivity of 5.76 \times 1 0^{- 3} S c m^{- 1} at298 K is$ (1) $2.88 S c m^{2} / m o l$ (2) $11.52 S c m^{2} / m o l$ (3) $0.086 S c m^{2} / m o l$ (4) $28.8 S c m^{2} / m o l$ 217. $In a cell that utilizes the reaction Z n_{(s)} + 2H_{(a q)}^{+} \to Zn_{(a q)}^{2 +} + H_{2 (g)}, addition of H_{2} S O_{4} to cathode compartment will :$ (1) $lower the E and shift equilibrium to the left.$ (2) $lower the E and shift the equilibrium to the right.$ (3) $increase the E and shift the equilibrium to the right.$ (4) $increase the E and shift the equilibrium to the left.$ 218. $The reaction occurs in which of the given galvanic cell? \frac{1}{2} H_{2} (g) + AgCl (s) ⇌ H^{+} (aq) + C l^{-} (aq) + Ag (s)$ (1) $Pt\| H_{2} (g)\|HCl(so l^{n})\|AgCl(s)\|Ag$ (2) $Ag\| AgCl(s)\|KCl(so l^{n})\| A g N O_{3} \|Ag$ (3) $Pt\| H_{2} (g)\|HCl(so l^{n})\| A g N O_{3} (so l^{n})\|Ag$ (4) $Pt\| H_{2} (g)\|KCl(so l^{n})\|AgCl(s)\|Ag$ 219. $For the reduction of silver ions with copper metal, the standard cell potential was found to b e + O .46 V at 2 5^{o} C . The value of standard Gibbs energy, ∆ G^{o} will be$ (1) $- 89.0 k J$ (2) $- 89.0 J$ (3) $- 44.5 k J$ (4) $- 98.0 k J$ 220. $How long (approximate) should water be electrolysed by passing through 100 amperes current so that the oxygen released can completely burn 27.66 g of diborane?$ (1) $3.2 hours$ (2) $1.6 hours$ (3) $6.4 hours$ (4) $0.8 hours$ 221. $Match List - I with List - II List-I (Parameter) (A) Cell constant (B) Molar conductivity (C) Conductivity (D) Degree of dissociation List-II (Unit) (I) S cm^{2} mol^{- 1} (II) Dimensionless (III) m^{- 1} (IV) Ω^{- 1} m^{- 1} of electrolyte Choose the most appropriate answer from the options given below :$ (1) $(A)-(III), (B)-(I), (C)-(IV), (D)-(II)$ (2) $(A)-(III), (B)-(I), (C)-(II), (D)-(IV)$ (3) $(A)-(I), (B)-(IV), (C)-(III), (D)-(II)$ (4) $(A)-(II), (B)-(I), (C)-(III), (D)-(IV)$ 222. $The emf of cell TI \| TI (0.001 M) \| (Cu^{2 +} (0.01 M)) Cu is 0.83 V at 298 K . It could be increased by :$ (1) $decreasing concentration of both Tl^{+} and Cu^{2 +} ions$ (2) $increasing concentration of Cu^{2 +} ions$ (3) $increasing concentration of T I^{+} ions$ (4) $increasing concentration of both TI+and Cu^{2 +} ions$ 223. $Given below are two statements : Statement I: The limiting molar conductivity of KCl (strong electrolyte) is higher compared to that o f C H_{3} COOH (weak electrolyte). Statement II: Molar conductivity decreases with decrease in concentration of electrolyte. In the light of the above statements, choose the answer from the options given below :$ (1) $Statement I is true but Statement II is false.$ (2) $Statement I is false but Statement II is true.$ (3) $Both Statement I and Statement II are true.$ (4) $Both Statement I and Statement II are false.$ 224. $Given:(i) C u^{2 +} + 2 e^{-} \to C u, E^{o} = 0.337 V (ii) C u^{2 +} + e^{-} \to C u^{+}, E^{o} = 0.153 V Electrode potential, E^{o} for the reaction, C u^{+} + e^{-} \to C u, will be$ (1) $0.90 V$ (2) $0.30 V$ (3) $0.38 V$ (4) $0.52 V$ 225. $Given below are half cell reactions: MnO_{4}^{-} + 8 H^{+} + 5 e^{-} \to Mn^{2 +} + 4 H_{2} O E_{Mn^{2 +} / MnO_{4}^{-}}^{o} = - 1.510 V \frac{1}{2} O_{2} + 2 H^{+} + 2 e^{-} \to H_{2} O E_{O_{2} / H_{2} O} = + 1.223 V Will the permanganate ion, MnO_{4}^{-} liberate O_{2} from water in the presence of an acid?$ (1) $No because E_{cell}^{0} = - 2.733 V$ (2) $Yes, because E_{cell}^{0} = + 0.287 V$ (3) $No, because E_{cell}^{0} = - 0.287 V$ (4) $Yes, because E_{cell}^{0} = + 2.733 V$ 226. $The standard electrode potential E^{Q} and its temperature coefficient for a cell are 2 V and -5 \times 1 0^{- 4} VK-1 at 300 K respectively. The cell reaction is Zn(s) + Cu^{2 +} (aq) ® Zn^{2 +} (aq) + Cu(s) The standard reaction enthalpy (D_{r} H^{Q}) at 300 K in kJ mol-1 is: (Use R = 8 J K^{-1} mol-1 and F = 96,000 Cmol^{-1})$ (1) $206.4$ (2) $-384.0$ (3) $192.0$ (4) $-412.8$ 227. $Under which of the following conditions E value of the cell, for the cell reaction given is maximum? Zn (s) + Cu^{2 +} (aq, c_{1}) ⟶ Cu (s) + Zn^{2 +} (aq, c_{2}) (\frac{2.303 R T}{F} at 298 K = 0.059 V, E_{Zn^{2 +} / Zn}^{\circ} = - 0.76 V, E_{Cu^{2 +} / Cu}^{\circ} = + 0.34 V)$ (1) $C_{1} = 0.1 M, C_{2} = 0.01 M$ (2) $C_{1} = 0.01 M, C_{2} = 0.1 M$ (3) $C_{1} = 0.1 M, C_{2} = 0.2 M$ (4) $C_{1} = 0.2 M, C_{2} = 0.1 M$ 228. $When an electric current is passed through acidified water, 112 mL of hydrogen gas at N.T.P was collected at the cathode in 965 seconds. The current passed, in ampere, is :$ (1) $2.0$ (2) $0.1$ (3) $0.5$ (4) $1.0$ 229. $On the basis of the information available from the reaction, 4/3 A l + O_{2} \to 2/3 A l_{2} O_{3}, ∆ G = - 827 k J m o l^{- 1} of O_{2}, the minimum e.m.f. required to carry out an electrolysis o f A 1_{2} O_{3} is (F = 96500 C mol^{- 1})$ (1) $2.14 V$ (2) $4.28 V$ (3) $6.42 V$ (4) $8.56 V$ 230. $The of different types of half cells are as follows : A B C D 1 x 1 0^{- 4} 2 x 1 0^{- 4} 0.1 x 1 0^{- 4} 0.2 x 1 0^{- 4} (Where E is the electromotive force) Which of the above half cells would be preferred to be used as reference electrode ?$ (1) $A$ (2) $B$ (3) $C$ (4) $D$ 231. $Choose the correct representation of conductometric titration of benzoic acid vs sodium hydroxide.$ (1) (2) (3) (4) 232. $In electrolysis of N a C l when Pt electrode is taken then H_{2} is liberated at cathode while with Hg cathode it forms sodium amalgam$ (1) $Hg is more inert than Pt$ (2) $More voltage is required to reduce H^{+} at Hg than at Pt$ (3) $Na is dissolved in Hg while it does not dissolve in Pt$ (4) $Conc. o f H^{+} ions is larger when Pt electrode is taken.$ 233. $A hypothetical electrochemical cell is shown below. A The emfmeasured i s + O .20 V. The cell reaction is$ (1) $A + B^{+} \to A^{+} + B$ (2) $A^{+} + B \to A + B^{+}$ (3) $A^{+} + e^{-} \to A; B^{+} + e^{-} \to B$ (4) $the cell reaction cannot be predicted.$ 234. $Which one of the following statements is correct for electrolysis of brine solution?$ (1) $C l_{2} is formed at cathode$ (2) $O_{2} is formed at cathode$ (3) $H_{2} is formed at anode$ (4) $O H^{-} is formed at cathode$ 235. $When 9.65 ampere current was passed for 1.0 hour into nitrobenzene in acidic medium, the amount of p-aminophenol produced is :$ (1) $109.0 g$ (2) $98.1 g$ (3) $9.81 g$ (4) $10.9 g$ 236. $At 298 K, the standard reduction potentials are 1.51 V for M n O_{4} - \| M n^{2 +}, 1.36 V for C l_{2} \|Cl- , 1.07 V for B r_{2} \|Br, and 0.54 V for I_{2} \|Ι-. At pH = 3, permanganate is expected to oxidize :$ (1) $Cl-, Br- and Ι-$ (2) $Br- and Ι-$ (3) $Cl- and Br-$ (4) $Ι- only$ 237. $The half cell reactions for rusting of iron are : 2 H^{+} + \frac{1}{2} O_{2} + 2e- \to H2O; Eº = +1.23 V & Fe^{2 +} + 2e- \to Fe ; Eº = - 0.44 V ΔGº (in kJ/mol) for the overall reaction is :$ (1) $- 76$ (2) $- 322$ (3) $- 122$ (4) $- 176$ 238. $Consider the above electrochemical cell where a metal electrode (M) is undergoing redox reaction by forming M^{+} (M \to M^{+} + e^{-}) . The cation M^{+} is present in two different concentrations c_{1} and c_{2} as shown above. Which of the following statement is correct for generating a positive cell potential?$ (1) $If c_{1} is present at cathode, then c_{1} < c_{2} .$ (2) $If c_{1} is present at anode, then c_{1} > c_{2} .$ (3) $If c_{1} is present at cathode, then c_{1} > c_{2} .$ (4) $If c_{1} is present at anode, then c_{1} = c_{2} .$ 239. $Given that the standard potentials (E^{0}) of C u^{2 +} / Cu and C u^{+} / Cu are 0.34 V and 0.522 V respectively, the (E^{0}) of C u^{2 +} / C u^{+} is:$ (1) $0.158 V$ (2) $- 0.158 V$ (3) $0.182 V$ (4) $- 0.182 V$ 240. $The specific conductance of a 0.1 N KC1 solution at 23 C is 0.012 o h m^{- 1} c m^{- 1} . The resistance of cell containing the solution at the same temperature was found to be 55 ohms. The cell constant will be$ (1) $0.918 c m^{- 1}$ (2) $0.66 c m^{- 1}$ (3) $1.142 c m^{- 1}$ (4) $1.12 c m^{- 1}$