Electrochemistry PYQs Set 8 (PDF)

Set 8 of 13 · Questions 211-240 of 363

In the print window choose “Save as PDF”. The file prints without a web address or date line.

Mere Teacher · Previous Year Questions JEE Main Chemistry · Electrochemistry · Set 8 (Q211-240)
Scan or visit mereteacher.com for free PYQ practice, timed CBT tests, step-by-step solutions and BroBot AI. Answers and solutions are free with a sign-up.
211. $The standard electrode potentials of A g^{+} /Ag is + 0.80 V and C u^{2 +} /Cu is + 0.34 V . If these electrodes are connected through a salt-bridge, which of the following statements is correct?$ (1) $Silver electrode acts as anode and E_{cell}^{\circ} is -0.34 V.$ (2) $Copper electrode acts as anode and E_{cell}^{\circ} is +0.46 V.$ (3) $Silver electrode acts as a cathode and E^{\circ} cell is -0.34 V.$ (4) $Copper electrode acts as cathode and E_{cell}^{\circ} is +0.46 V.$ 212. $A current of 15.0 amperes is passed through a solution of CrCl_{2} for 45 minutes. The volume of Cl_{2} (in L) obtained at the anode at 1 atm and 273 K is around (1 F = 96500 C mol^{- 1}), At. wt. of Cl = 35.5, R = 0.082 L-atmK^{- 1} mol^{- 1})$ (1) $4.7$ (2) $3.7$ (3) $2.7$ (4) $5.7$ 213. $Which one of the following has a potential more than zero?$ (1) $Pt, \frac{1}{2} H_{2} (1 atm) / HCl (1 M)$ (2) $Pt, (\frac{1}{2} H_{2} (1 atm)) HCl (2 M)$ (3) $Pt, (\frac{1}{2} H_{2} (1 atm)) HCl (0.1 M)$ (4) $Pt, (\frac{1}{2} H_{2} (1 atm)) HCl (0.5 M)$ 214. $In 3d series, the metal having the highest M^{2 +} /M standard electrode potential is$ (1) $Cr$ (2) $Fe$ (3) $Cu$ (4) $Zn$ 215. $A 1_{2} O_{3} is reduced by electrolysis at low potentials and high currents. I f 4.0 \times 1 0^{4} amperes of current is passed through molten A 1_{2} O_{3} for 6 hours, what mass of aluminium is produced? (Assume 100% current efficiency, at. mass of Al = 27 g m o 1^{- 1}) .$ (1) $8. 1 \times 1 0^{4} g$ (2) $2.4 \times 1 0^{5} g$ (3) $1. 3 \times 1 0^{4} g$ (4) $9.0 \times 1 0^{3} g$ 216. $Impure copper containing Fe, Au, Ag as impurities is electrolytically refined. A current of 140 A for 482.5 s decreased the mass of the anode by 22.26 g and increased the mass of cathode by 22.011 g . Percentage of iron in impure copper is (Given: molar mass Fe = 55.5 g mol^{- 1}, molar mass Cu = 63.54 g mol^{- 1})$ (1) $0.95$ (2) $0.85$ (3) $0.97$ (4) $0.90$ 217. $What pressure (bar) of H_{2} would be required to make emf of hydrogen electrode zero in pure water at 25^{\circ} C ?$ (1) $10^{- 7}$ (2) $0.5$ (3) $1$ (4) $10^{- 14}$ 218. $The standard Gibbs energy for the given cell reaction in kJ mol^{- 1} at 298 K is: Zn (s) + Cu^{2 +} (aq) \to Zn^{2 +} (aq) + Cu (s) E^{\circ} = 2 V at 298 K (Faraday's constant, (F = 96000 C mol^{- 1})$ (1) $- 384$ (2) $384$ (3) $192$ (4) $- 192$ 219. $Given that E_{O_{2} / H_{2} O}^{\circ} = + 1.23 V E_{S_{2} O_{8}^{2 -} / SO_{4}^{2 -}}^{\circ} = 2.05 V E_{Br_{2} / Br^{-}}^{\circ} = + 1.09 V E_{Au^{3 +} / Au}^{\circ} = + 1.4 V The strongest oxidising agent is:$ (1) $Au^{3 +}$ (2) $O_{2}$ (3) $S_{2} O_{8}^{2 -}$ (4) $Br_{2}$ 220. $A reaction Ni_{(s)} + Cu^{++} (1 M) \to Ni^{++} (1 M) + Cu_{(s)} occurs in a cell. Calculate E_{cell}^{\circ} if E_{Cu}^{\circ} = 0.337 V and E_{Ni}^{\circ} = - 0.257 V .$ (1) $0.594 V$ (2) $- 0.594 V$ (3) $- 0.08 V$ (4) $0.08 V$ 221. $How many coulombs of electricity are required for the oxidation of one mol of water to dioxygen?$ (1) $1.93 \times 10^{4} C$ (2) $19.3 \times 10^{5} C$ (3) $9.65 \times 10^{4} C$ (4) $1.93 \times 10^{5} C$ 222. $The equilibrium constant of the reaction: C u_{(s)} + 2 A g_{(}^{+}_{a q)} \to C u_{(}^{2}_{a}_{q)}^{+} + 2 A g_{(s)}; E^{o} = 0.46 V at 298 K is$ (1) $2.0 \times 1 0^{10}$ (2) $4.0 \times 1 0^{10}$ (3) $4.0 \times 1 0^{15}$ (4) $2.4 \times 1 0^{10}$ 223. $In the electrochemical cell: Zn ∣ ZnSO_{4} (0.01 M) ∥ CuSO_{4} (1.0 M) ∣ Cu, the emfof this Daniell cell is E_{1} . When the concentration o f Z n S O_{4} is changed to 1.0 M and that of C u S O_{4} changed to 0.01 M, the emf changes to E_{2} . From the followings, which one is the relationship between E_{1} and E_{2} ? (Given, R T l F = 0.059)$ (1) $E_{1} < E_{2}$ (2) $E_{1} > E_{2}$ (3) $E_{2} = 0 \neq = E_{1}$ (4) $E_{1} = E_{2}$ 224. $Given below are two statements: Statement I: For KI, molar conductivity increases steeply with dilution. Statement II: For carbonic acid, molar conductivity increases slowly with dilution. In the light of the above statements, choose the correct answer from the options given below:$ (1) $Both Statement I and Statement II are true$ (2) $Both Statement I and Statement II are false$ (3) $Statement I is true but Statement II is false$ (4) $Statement I is false but Statement II is true$ 225. $In the cell, Pt(s) \| H_{2} (g,1bar) \| HCl(aq) \| AgCl (s) \| Ag(s)\| Pt(s) The cell potential is 0.92 V when a 1 0^{-6} molal HCl solution is used. The standard electrode potential of (AgCl / Ag, C l^{-)} electrode is : {Given, \frac{2.303 R T}{F} = 0.06 V at 298k}$ (1) $0.76 V$ (2) $0.20 V$ (3) $0.94 V$ (4) $0.40 V$ 226. $E_{C u^{2 +} \| Cu}^{0} = + 0.34 V E_{Zn^{2 +} \| Zn}^{0} = - 0.76 V Identify the incorrect statement from the option below for the above cell:$ (1) $If E_{ext} < 1.1 V ., Zn dissolves at anode and Cu deposits at cathode$ (2) $If E_{ext} = 1.1 V, no flow of e^{-} or current occurs.$ (3) $If E_{ext} > 1.1 V, e^{-} flows from Cu to Zn.$ (4) $If E_{ext} > 1.1 V, Zn dissolves at Zn electrode and Cu deposits at Cu electrode.$ 227. $Calculate the standard cell potential (in V) of the cell in which following reaction takes place : Fe^{2 +} (aq) + Ag^{+} (aq) \to Fe^{3 +} (aq) + Ag (s) Given that E_{Ag^{+} / Ag}^{0} = xV E_{Fe^{2 +} / Fe}^{0} = yV E_{Fe^{3 +} / Fe}^{0} = zV$ (1) $x - z$ (2) $x - y$ (3) $x + 2 y - 3 z$ (4) $x + y - z$ 228. $For the disproportionation of copper 2 C u^{+} \to C u^{2 +} + C u, E^{o} is (Given: E^{o} for C u^{2 +} / C u is 0.34 V and E^{o} for C u^{2 +} / C u^{+} is 0.15 V.)$ (1) $0.49 V$ (2) $- 0.19 V$ (3) $0.38 V$ (4) $- 0.38 V$ 229. $Zinc can be coated on iron to produce galvanized iron but the reverse is not possible. It is because$ (1) $zinc is lighter than iron$ (2) $zinc has lower melting point than iron$ (3) $zinc has lower negative electrode potential than iron$ (4) $zinc has higher negative electrode potential than iron.$ 230. $A conductivity cell with two electrodes (dark side) are half filled with infinitely dilute aqueous solution of a weak electrolyte. If volume is doubled by adding more water at constant temperature, the molar conductivity of the cell will -$ (1) $decrease sharply$ (2) $increase sharply$ (3) $remain same or can not be measured accurately$ (4) $depend upon type of electrolyte$ 231. $Given below are the half-cell reactions : M n^{2 +} + 2 e^{-} \to Mn ; Eº = -1.18 V 2(M n^{3 +} + e^{-} \to M n^{2 +}) ; Eº = +1.51 V The Eº for 3 M n^{2 +} \to Mn + 2 M n^{3 +} will be :$ (1) $-2.69 V ; the reaction will not occur$ (2) $-2.69 V ; the reaction will occur$ (3) $-0.33 V ; the reaction will not occur$ (4) $-0.33 V ; the reaction will occur$ 232. $When an aqueous solution of CuCl_{2} is electrolysed using Pt inert electrodes, the reaction at cathode and anode respectively are$ (1) $4 H_{2} O (l) + 4 e^{-} 2 H_{2} (g) + 4 O H_{2} (aq); 2 H_{2} O (l) - 4 e^{-} O_{2} (g) + 4 H^{+} (aq)$ (2) $2C u^{2 +} (aq) + 4 e^{-} 2Cu (s); 2 H_{2} O (l) - 4 e^{-} O_{2} (g) + 4 H^{+} (aq)$ (3) $C u^{2 +} (aq) + 2 e^{-} Cu (s); 2C l^{-} (aq) - 2 e^{-} C l_{2} (g)$ (4) $2 H_{2} O (l) + 2 e^{-} H_{2} (g) + 2 O H (aq); 2C l^{-} (aq) - 2 e^{-} C l_{2} (g)$ 233. $For lead storage battery pick the correct statements (A) During charging of battery, P b S O_{4} on anode is converted into P b O_{2} (B) During charging of battery, P b S O_{4} on cathode is converted into P b O_{2} (C) Lead storage battery consists of grid of lead packed with P b O_{2} as anode (D) Lead storage battery has -38% solution of sulphuric acid as an electrolyte Choose the correct answer from the options given below:$ (1) $A, B, D only$ (2) $B, C, D only$ (3) $B, C only$ (4) $B, D only$ 234. $An acidic solution of dichromate is electrolyzed for 8 minutes using 2A current. As per the following equation The amount of obtained was 0.104 g. The efficiency of the process (in\%) is (Take: F=96000C, At. Mass of chromium = 52)$ 235. $One Faraday of electricity liberates x \times 10^{- 1} gram atom of copper from copper sulphate, x is__________$ 236. $A solution of F e_{2} (S O_{4})_{3} is electrolyzed for ‘x’ min with a current of 1.5 A to deposit 0.3482 g of Fe.The value of x is______. [nearest integer] Given : 1F = 96500 C m o l^{- 1} Atomic mass of Fe = 56 g m o l^{- 1}$ 237. $The molar conductivities at infinite dilution ofbarium chloride, sulphuricarid and hydrochloric acid are 280, 860 and 426 Scm^{2} mol^{- 1} respectively. Themolar conductivity at infinite dilution of barium sulphate is S cm^{2} mol^{- 1} ( Round off to the Nearest Integer).$ 238. $An oxidation -reduction reaction in which 3 electrons are transferred has a ∆ G ° of 17.37 kJ mol^{- 1} at 25°C. The value of E °_{cell} (in V) is \times 10^{- 2} (1F = 96,500 C mol^{- 1})$ 239. $Cu(s) + S n^{2 +} (0.001M) \to C u^{2 +} (0.01M) + Sn(s) The Gibbs free energy change for the above reaction at 298 K is x \times 1 0^{- 1} kJ m o l^{- 1}; The value of x is______. [nearest integer] [Given :]$ 240. $The limiting molar conductivities of Nal, N a N O_{3} and A g N O_{3} are 12.7, 12.0 and 13.3 mS m^{2} m o l^{- 1}, respectively (all at 25°C). The limiting molar conductivity of Agl at this temperature is _____ mS m^{2} m o l^{- 1}$