Electrochemistry PYQs Set 10 (PDF)

Set 10 of 13 · Questions 271-300 of 363

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Mere Teacher · Previous Year Questions JEE Main Chemistry · Electrochemistry · Set 10 (Q271-300)
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271. $When an electric current is passed through acidified water, 112 mL of hydrogen gas at N.T.P was collected at the cathode in 965 seconds. The current passed, in ampere, is :$ (1) $2.0$ (2) $0.1$ (3) $0.5$ (4) $1.0$ 272. $On the basis of the information available from the reaction, 4/3 A l + O_{2} \to 2/3 A l_{2} O_{3}, ∆ G = - 827 k J m o l^{- 1} of O_{2}, the minimum e.m.f. required to carry out an electrolysis o f A 1_{2} O_{3} is (F = 96500 C mol^{- 1})$ (1) $2.14 V$ (2) $4.28 V$ (3) $6.42 V$ (4) $8.56 V$ 273. $The of different types of half cells are as follows : A B C D 1 x 1 0^{- 4} 2 x 1 0^{- 4} 0.1 x 1 0^{- 4} 0.2 x 1 0^{- 4} (Where E is the electromotive force) Which of the above half cells would be preferred to be used as reference electrode ?$ (1) $A$ (2) $B$ (3) $C$ (4) $D$ 274. $Choose the correct representation of conductometric titration of benzoic acid vs sodium hydroxide.$ (1) (2) (3) (4) 275. $In electrolysis of N a C l when Pt electrode is taken then H_{2} is liberated at cathode while with Hg cathode it forms sodium amalgam$ (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) $Conc. o f H^{+} ions is larger when Pt electrode is taken.$ 276. $A hypothetical electrochemical cell is shown below. A The emfmeasured i s + O .20 V. The cell reaction is$ (1) $A + B^{+} \to A^{+} + B$ (2) $A^{+} + B \to A + B^{+}$ (3) $A^{+} + e^{-} \to A; B^{+} + e^{-} \to B$ (4) $the cell reaction cannot be predicted.$ 277. $Which one of the following statements is correct for electrolysis of brine solution?$ (1) $C l_{2} is formed at cathode$ (2) $O_{2} is formed at cathode$ (3) $H_{2} is formed at anode$ (4) $O H^{-} is formed at cathode$ 278. $When 9.65 ampere current was passed for 1.0 hour into nitrobenzene in acidic medium, the amount of p-aminophenol produced is :$ (1) $109.0 g$ (2) $98.1 g$ (3) $9.81 g$ (4) $10.9 g$ 279. $At 298 K, the standard reduction potentials are 1.51 V for M n O_{4} - \| M n^{2 +}, 1.36 V for C l_{2} \|Cl- , 1.07 V for B r_{2} \|Br, and 0.54 V for I_{2} \|Ι-. At pH = 3, permanganate is expected to oxidize :$ (1) $Cl-, Br- and Ι-$ (2) $Br- and Ι-$ (3) $Cl- and Br-$ (4) $Ι- only$ 280. $The half cell reactions for rusting of iron are : 2 H^{+} + \frac{1}{2} O_{2} + 2e- \to H2O; Eº = +1.23 V & Fe^{2 +} + 2e- \to Fe ; Eº = - 0.44 V ΔGº (in kJ/mol) for the overall reaction is :$ (1) $- 76$ (2) $- 322$ (3) $- 122$ (4) $- 176$ 281. $Consider the above electrochemical cell where a metal electrode (M) is undergoing redox reaction by forming M^{+} (M \to M^{+} + e^{-}) . The cation M^{+} is present in two different concentrations c_{1} and c_{2} as shown above. Which of the following statement is correct for generating a positive cell potential?$ (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) $If c_{1} is present at anode, then c_{1} = c_{2} .$ 282. $Given that the standard potentials (E^{0}) of C u^{2 +} / Cu and C u^{+} / Cu are 0.34 V and 0.522 V respectively, the (E^{0}) of C u^{2 +} / C u^{+} is:$ (1) $0.158 V$ (2) $- 0.158 V$ (3) $0.182 V$ (4) $- 0.182 V$ 283. $The specific conductance of a 0.1 N KC1 solution at 23 C is 0.012 o h m^{- 1} c m^{- 1} . The resistance of cell containing the solution at the same temperature was found to be 55 ohms. The cell constant will be$ (1) $0.918 c m^{- 1}$ (2) $0.66 c m^{- 1}$ (3) $1.142 c m^{- 1}$ (4) $1.12 c m^{- 1}$ 284. $If the standard electrode potential for a cell is 2 V at 300 K, the equilibrium constant (K) for the reaction Zn(s) + C u^{2 +} (aq) ⇌ Z n^{2 +} (aq) + Cu(s) at 300 K is approximately (R = 8 J K^{-1} mol, F = 96000 C m o l^{-1})$ (1) $e^{320}$ (2) $e^{-80}$ (3) $e^{160}$ (4) $e^{-160}$ 285. $Find the emf of the cell in which the following reaction takes place at 298 K Ni (s) + 2A g^{+} (0.001 M) \to N i^{2 +} (0.001 M) + 2Ag (s) (Given that E_{ce l l}^{\circ} = 1.05 V, \frac{2.303 R T}{F} = 0.059 at 298 K)$ (1) $1.05 V$ (2) $1.0385 V$ (3) $1.385 V$ (4) $0.9615 V$ 286. $The standard reduction potential values of some of the p -block ions are given below. Predict the one with the strongest oxidising capacity.$ (1) $E_{Pb^{4 +} / Pb^{2 +}}^{⊖} = + 1.67 V$ (2) $E_{Sn^{4 +} / Sn^{2 +}}^{⊖} = + 1.15 V$ (3) $E_{Al^{3 +} / Al}^{⊖} = - 1.66 V$ (4) $E_{T 1}^{⊖} / Tl /2.26 V$ 287. $In fuel cells, ______ are used as catalysts.$ (1) $zinc-mercury$ (2) $platinum-palladium$ (3) $nickel-cadmium$ 288. $Given: E_{M n^{7 +} / M n^{2 +}}^{\circ} = 1.5 V and E_{M n^{4 +} / M n^{2 +}}^{\circ} = 1.2 V, then E_{M n^{7 +} / M n^{4 +}}^{\circ} is$ (1) $0.3 V$ (2) $0.1 V$ (3) $1.7 V$ (4) $2.1 V$ 289. $Standard hydrogen electrode (SHE) is a$ (1) $primary reference electrode$ (2) $secondary reference electrode$ (3) $metal - sparingly soluble salt electrode$ (4) $metal metal ion electrode.$ 290. $Kohlrausch’s law states that at$ (1) $Infinite dilution, each ion makes definite contribution to conductance of an electrolyte whatever be the nature of the other ion of the electrolyte$ (2) $Infinite dilution, each ion makes definite contribution to equivalent conductance of an electrolyte, whatever be the nature of the other ion of the electrolyte$ (3) $Finite dilution, each ion makes definite contribution to equivalent conductance of an electrolyte, whatever be the nature of the other ion of the electrolyte$ (4) $Infinite dilution each ion makes definite contribution to equivalent conductance of an electrolyte depending on the nature of the other ion of the electrolyte.$ 291. $A and B are two metals. The standard reduction potential of A^{+} (aq) / A (s) and B^{+} (aq) / B (s) are - 0.5 V and + 0.5 V respectively. What is the log K_{C} value for the following reaction at 298 K ? A (s) + B^{+} (aq) ⇌ A^{+} (aq) + B (s) (Given (: \frac{2.303 RT}{F} = 0.06 V)$ (1) $\frac{6}{100}$ (2) $\frac{100}{6}$ (3) $\frac{6}{200}$ (4) $\frac{200}{6}$ 292. $At 298 K, the standard reduction potential for Cu^{2 +} /Cu electrode is 0.34V. Given : K_{s p} C u (O H)_{2} = 1 x 10-20 Take \frac{2.303 RT}{F} = 0.059 V The reduction potential at pH = 14 for the above couple is (-)x \times 10-2 V. The value of x is$ 293. $For the reaction 2 Fe^{3 +} (aq) + 2 I^{-} (aq) \to 2 Fe^{2 +} (aq) + I_{2} (s) the magnitude of the standard molar free energy change, Δ_{r} G_{m}^{\circ} = - kJ (Round off to the Nearest Integer).$ 294. $For the galvanic cell, Zn(s) + C u^{2 +} (0.02M) \to Z n^{2 +} (0.04M) + Cu(s), E_{ce l l} =\dots\times 1 0^{- 2} V. (Nearest integer) [Use : \frac{2.303 R T}{F} =0.059V]$ 295. $Given below is the plot of the molar conductivity vs concentration for KCl in aqueous solution. If, for the higher concentration of KCl solution, the resistance of the conductivity cell is 100Ω, then the resistance of the same cell with the dilute solution is ' x' Ω The value of x is (Nearest integer)$ 296. $The amount of electricity in Coulomb required for the oxidation of 1 mol of H_{2} O to O_{2} is ________\times 1 0^{5} C .$ 297. $A volume of x mL of 5 M NaHCO_{3} solution was mixed with 10 mL of 2 M H_{2} CO_{3} solution to make an electrolytic buffer. If the same buffer was used in the following electrochemical cell to record a cell potential of 235.3 mV , then the value of x =____mL (nearest integer). Sn (s) (Sn (OH)_{6}^{2 -} (0.5 M)) HSnO_{2}^{-} (0.05 M) (OH^{-}) Bi_{2} O_{3} (s) ∣ Bi (s) Consider up to one place of decimal for intermediate calculations. Given: E_{\frac{( Sn ( OH ) _{6} ) ^{2 -}}{HSnO _{2}^{-}}}^{\circ} = - 0.90 V E_{\frac{Bi _{2} O _{3}}{Bi}}^{\circ} = - 0.44 V p K_{a} (H_{2} CO_{3}) = 6.11 \frac{2.303 RT}{F} = 0.059 V Antilog (1.29) = 19.5$ 298. $Consider the following electrochemical cell at 298 K Pt (HSnO_{2}^{-} (aq)) Sn (OH)_{6}^{2 -} (aq) (OH^{-} (aq)) Bi_{2} O_{3} (s) ∣ Bi (s) . If the reaction quotient at a given time is 10^{6}, then the cell EMF (E_{cell}) is____\times 10^{- 1} V (Nearest integer). Given the standard half-cell reduction potential as E_{Bi_{2} O_{3} / Bi, OH^{-}}^{\circ} = - 0.44 V and E_{Sn (OH)_{6}^{2 -} / HSnO_{2}^{-}, OH^{-}}^{\circ} = - 0.90 V$ 299. $The number of correct statements from the following is........... (A) E_{ce l l} is an intensive parameter (B) A negative E° means that the redox couple is a stronger reducing agent than the H^{+} / H_{2} couple. (C) The amount of electricity required for oxidation or reduction depends on the stoichiometry of the electrode reaction. (D) The amount of chemical reaction which occurs at any electrode during electrolysis by a current is proportional to the quantity of electricity passed through the electrolyte$ 300. $Consider the following electrochemical cell : Pt (O_{2} (g) (1 bar)) HCl (aq) ‖ M^{2 +} (aq, 1.0 M) ∣ M (s) The pH above which, oxygen gas would start to evolve at anode is____(nearest integer). (Given : E^{o}_{M^{2 +} / M} = 0.994 V E^{o}_{O_{2} / H_{2} O} = 1.23 V) standard reduction potential]$