Electrochemistry PYQs Set 10 (PDF)

Set 10 of 10 · Questions 271-293 of 293

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Mere Teacher · Previous Year Questions NEET Chemistry · Electrochemistry · Set 10 (Q271-293)
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271. $Equivalent conductances of B a^{2 +} and C l^{-} ions are 127 and 76 o h m^{- 1} c m^{- 1} e q^{- 1} respectively. Equivalent conductance of B a C 1_{2} at infinite dilution is$ (1) $139.5$ (2) $101.5$ (3) $203$ (4) $279$ 272. $Standard electrode potential for S n^{4 +} / S n^{2 +} couple is + 0.15 V and that for the C r^{3 +} / C r couple is—O.74 V These two couples in their standard state are connected to make a cell. The cell potential will be$ (1) $+ 1.19 V$ (2) $+ 0.89 V$ (3) $+ 0.18 V$ (4) $+ 1.83 V$ 273. $The molar conductivity of a weak electrolyte when plotted against the square root of its concentration, which of the following is expected to be observed ?$ (1) $A small decrease in molar conductivity is observed at infinite dilution.$ (2) $Molar conductivity decreases sharply with increase in concentration.$ (3) $A small increase in molar conductivity is observed at infinite dilution.$ (4) $Molar conductivity increases sharply with increase in concentration.$ 274. $The molar conductivity of a conductivity cell filled with 10 moles of 20 mL NaCl solution is \land_{m l} and that of 20 moles another identical cell heaving 80 mL NaCl solution is \land_{m 2}, The conductivities exhibited by these two cells are same. The relationship between \land_{m 2} and \land_{m l} is$ (1) $\land_{m 2} =2 \land_{m l}$ (2) $\land_{m 2} = \land_{m l} /2$ (3) $\land_{m 2} = \land_{m l}$ (4) $\land_{m 2} =4 \land_{m l}$ 275. $What is the SI unit of conductivity?$ (1) $Sm$ (2) $S m^{- 1}$ (3) $S m^{2}$ (4) $S m^{- 2}$ 276. $The electrolytes usually used in the electroplating of gold and silver, respectively, are:$ (1) $[Au(CN)_{2}]^{-} and [A g C l_{2}]^{-}$ (2) $[Au(N H_{3})_{2}]^{+} and [Ag(CN)_{2}]^{-}$ (3) $[Au(CN)_{2}]^{-} and [Ag(CN)_{2}]^{-}$ (4) $[Au(OH)_{4}]^{-} and [Ag(OH)_{2}]^{-}$ 277. $Given: F e^{3 +} (aq) + e^{-} ® F e^{2 +} (aq); Eº = + 0.77 V A l^{3 +} (aq) + 3 e^{-} ® Al(s); Eº = -1.66 V B r_{2} (aq) + 2 e^{-} ® 2 B r^{-}; Eº = +1.09 V Considering the electrode potentials, which of the following represents the correct order of reducing power?$ (1) $F e^{2 +} < Al < B r^{-}$ (2) $B r^{-} < F e^{2 +} < Al$ (3) $Al < B r^{-} < F e^{2 +}$ (4) $Al < F e^{2 +} < B r^{-}$ 278. $An aqueous solution of CuSO_{4} is subjected to electrolysis using inert electrodes. The pH of the solution will$ (1) $increase$ (2) $remains unchanged$ (3) $decrease$ (4) $increase or decrease depending on the strength of the current,$ 279. $A current of 10.0 A flows for 2.00 h through an electrolytic cell containing a molten salt of metal X. This results in the decomposition of 0.250 mol of metal X at the cathode. The oxidation state of X in the molten salt is : (F = 96,500 C)$ (1) $1 +$ (2) $2 +$ (3) $3 +$ (4) $4 +$ 280. $One of the commonly used electrode is calomel electrode. Under which of the following categories, calomel electrode comes?$ (1) $Oxidation - Reduction electrodes$ (2) $Metal ion - Metal electrodes$ (3) $Gas - Ion electrodes$ (4) $Metal - Insoluble Salt - Anion electrodes$ 281. $The conductivity of an electrolytic solution decreases on dilution due to$ (1) $decrease in number of ions per unit volume$ (2) $increase in ionic mobility of ions$ (3) $increase in percentage ionisation$ (4) $increase in number of ions per unit volume.$ 282. $Match List I with List II List - I (Cell) A. Leclanche cell B. Ni - Cd cell C. Fuel cell D. Mercury cell List - II (Use/Property/Reaction) I . Converts energy of combustion into electrical energy II. Does not involve any ion in solution and is used in hearing aids III. Rechargeable IV. Reaction at anode Zn \to Zn^{2 +} + 2 e^{-} Choose the correct answer from the options given below:$ (1) $A-II, B-III, C-IV, D-I$ (2) $A-I, B-II, C-III, D-IV$ (3) $A-III, B-I, C-IV, D-II$ (4) $A-IV, B-III, C-I, D-II$ 283. $A device that converts energy of combustion of fuels like hydrogen and methane, directly into electrical energy is known as$ (1) $dynamo$ (2) $Ni‐Cd cell$ (3) $fuel cell$ (4) $electrolytic cell.$ 284. $How many electrons would be required to deposit 6.35 g of copper at the cathode during the electrolysis of an aqueous solution of copper sulphate? (Atomic mass of copper = 63.5 u, N_{A} = Avogadro's constant).$ (1) $\frac{N _{A}}{20}$ (2) $\frac{N _{A}}{10}$ (3) $\frac{N _{A}}{5}$ (4) $\frac{N _{A}}{2}$ 285. $Which among the following solutions is not used in determination of the cell constant?$ (1) $10^{- 2} MKCl$ (2) $10^{- 1} MKCl$ (3) $1 MKCl$ (4) $Saturated KCl$ 286. $The correct order of reduction potentials of the following pairs is A. C l_{2} / C l^{-} B. I_{2} / I^{-} C. A g^{+} / A g D. N a^{+} /Na E. L i^{+} /Li Choose the correct answer from the options given below.$ (1) $A>C>B>D>E$ (2) $A>B>C>D>E$ (3) $A>C>B>E>D$ (4) $A>B>C>E>D$ 287. $A button cell used in watches function as following: Z n_{(s)} + A g_{2} O_{(s)} + H_{2} O_{(l)} ⇌ 2 A g_{(s)} + Z n_{(a q)}^{2 +} + 2 O H_{(a q)}^{-} If half-cell potentials are Z n_{(}^{2}_{a}_{q)}^{+} + 2 e^{-} \to Z n_{(s)}; E^{o} = - O .76 V A g_{2} O_{(s)} + H_{2} O + 2 e^{-} \to 2 A g_{(s)} + 2 O H_{(}^{-}_{a q)}, E^{o} = 0.34 V The cell potential will be$ (1) $0.84 V$ (2) $1.34 V$ (3) $1.10 V$ (4) $0.42 V$ 288. $The standard electrode potentials of four metals A, B, C and D are -1.2 V, 0.6 V, 0.85 V and -0.76 V, respectively. The sequence of deposition of metals on applying potential is:$ (1) $A, C, B, D$ (2) $B, D, C, A$ (3) $C, B, D, A$ (4) $D, A, B, C$ 289. $Reduction potential for the following half‐cell reactions areZn = Z n^{2 +} + 2 e^{-}; E^{o} = + O .76 V;Fe = F e^{2 +} + 2 e^{-}; E^{o} = + O .44 V.The EMF for the cell reaction F e^{2 +} + Z n \to Z n^{2 +} + F e will be$ (1) $- 0.32 V$ (2) $+ 1.20 V$ (3) $- 1.20 V$ (4) $+ 0.32 V$ 290. $In a galvanic cell, the salt bridge$ (1) $does not participate chemically in the cell reaction.$ (2) $stops the diffusion of ions from one electrode to another.$ (3) $is necessary for the occurrence of the cell reaction.$ (4) $ensures mixing of the two electrolytic solutions.$ 291. $Which of the following is incorrect ?$ (1) $Λ °_{m} NaCl - Λ °_{m} NaBr = Λ °_{m} KCl - Λ °_{m} KBr$ (2) $Λ °_{m} H_{2} O = Λ °_{m} HCl + Λ °_{m} NaOH - Λ °_{m} NaCl$ (3) $Λ °_{m} NaBr - Λ °_{m} Nal = Λ °_{m} KBr - Λ °_{m} NaBr$ (4) $Λ °_{m} NaCl - Λ °_{m} KCl = Λ °_{m} NaBr - Λ °_{m} KBr$ 292. $A secondary cell is one which$ (1) $can be recharged$ (2) $can be recharged by passing current through it in the same direction$ (3) $can be recharged by passing current through it in the opposite direction$ (4) $cannot be recharged.$ 293. $Identify the correct statement:$ (1) $Corrosion of iron can be minimized by forming an impermeable barrier at its surface.$ (2) $Iron corrodes in oxygen-free water.$ (3) $Iron corrodes more rapidly in salt water because its electrochemical potential is higher.$ (4) $Corrosion of iron can be minimized by forming a contact with another metal with a higher reduction potential.$