Electrochemistry PYQs Set 9 (PDF)

Set 9 of 10 · Questions 241-270 of 293

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Mere Teacher · Previous Year Questions NEET Chemistry · Electrochemistry · Set 9 (Q241-270)
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241. $If the standard electrode potential for a cell is 2 V at 300 K, the equilibrium constant (K) for the reaction Zn(s) + C u^{2 +} (aq) ⇌ Z n^{2 +} (aq) + Cu(s) at 300 K is approximately (R = 8 J K^{-1} mol, F = 96000 C m o l^{-1})$ (1) $e^{320}$ (2) $e^{-80}$ (3) $e^{160}$ (4) $e^{-160}$ 242. $Find the emf of the cell in which the following reaction takes place at 298 K Ni (s) + 2A g^{+} (0.001 M) \to N i^{2 +} (0.001 M) + 2Ag (s) (Given that E_{ce l l}^{\circ} = 1.05 V, \frac{2.303 R T}{F} = 0.059 at 298 K)$ (1) $1.05 V$ (2) $1.0385 V$ (3) $1.385 V$ (4) $0.9615 V$ 243. $The standard reduction potential values of some of the p -block ions are given below. Predict the one with the strongest oxidising capacity.$ (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) $E_{T 1}^{⊖} / Tl /2.26 V$ 244. $In fuel cells, ______ are used as catalysts.$ (1) $zinc-mercury$ (2) $platinum-palladium$ (3) $nickel-cadmium$ 245. $Given: E_{M n^{7 +} / M n^{2 +}}^{\circ} = 1.5 V and E_{M n^{4 +} / M n^{2 +}}^{\circ} = 1.2 V, then E_{M n^{7 +} / M n^{4 +}}^{\circ} is$ (1) $0.3 V$ (2) $0.1 V$ (3) $1.7 V$ (4) $2.1 V$ 246. $Standard hydrogen electrode (SHE) is a$ (1) $primary reference electrode$ (2) $secondary reference electrode$ (3) $metal - sparingly soluble salt electrode$ (4) $metal metal ion electrode.$ 247. $Kohlrausch’s law states that at$ (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) $Infinite dilution each ion makes definite contribution to equivalent conductance of an electrolyte depending on the nature of the other ion of the electrolyte.$ 248. $A and B are two metals. The standard reduction potential of A^{+} (aq) / A (s) and B^{+} (aq) / B (s) are - 0.5 V and + 0.5 V respectively. What is the log K_{C} value for the following reaction at 298 K ? A (s) + B^{+} (aq) ⇌ A^{+} (aq) + B (s) (Given (: \frac{2.303 RT}{F} = 0.06 V)$ (1) $\frac{6}{100}$ (2) $\frac{100}{6}$ (3) $\frac{6}{200}$ (4) $\frac{200}{6}$ 249. $The standard electrode potential E^{0} and its temperature coefficient (\frac{dE ^{0}}{dT}) for a cell are 2 V and - 5 \times 10^{- 4} VK^{- 1} at 300 K respectively. The cell reaction is: Zn (s) + Cu^{2 +} (aq) \to Zn^{2 +} (aq) + Cu The standard reaction enthalpy (Δ_{r} H^{0}) at 300 K in kJ mol^{- 1} is, (Use R = 8 JK^{- 1} mol^{- 1} and F = 96, 000 C mol^{- 1})$ (1) $- 412.8$ (2) $- 384.0$ (3) $192.0$ (4) $206.4$ 250. $The electrolyte used in mercury cell iS$ (1) $Moist paste of NH_{4} Cl and ZnCl_{2}$ (2) $38% solution of H_{2} SO_{4}$ (3) $Paste of KOH and ZnO$ (4) $Paste of MgCl_{2} and HgO$ 251. $In the given electrochemical cell, Ag (s) \| AgCl (s) \| FeCl_{2} (aq), FeCl_{3} (aq) ∣ Pt (s) at 298 K , the cell potential (E_{cell}) will increase when :(A) Concentration of Fe2+ is increased.(B) Concentration of Fe3+ is decreased.(C) Concentration of Fe2+ is decreased.(D) Concentration of Fe3+ is increased.(E) Concentration of Cl^{-} is increased. Choose the correct answer from the options given below:$ (1) $(B) Only$ (2) $(A) and (E) Only$ (3) $(C) (D) and (E) Only$ (4) $A and B Only$ 252. $Given below are two statements: Statement I: Mohr's salt is composed of only three types of ions-ferrous, ammonium and sulfate. Statement II: If the molar conductance at infinite dilution for ferrous, ammonium and sulfate ions are x_{1}, x_{2} and x_{3} S cm^{2} mol^{- 1}, respectively then the molar conductance for Mohr's salt solution at infinite dilution would be given by x_{1} + x_{2} + 2 x_{3} In the light of the given statements, choose the correct answer from the options given below:$ (1) $Both Statements I and Statement II are true$ (2) $Statement I is true but Statement II is false$ (3) $Both Statements I and Statement II are false$ (4) $Statement I is false but Statement II is true$ 253. $Given below are two statements: 1 M aqueous solutions of each of Cu (NO_{3})_{2}, AgNO_{3}, Hg_{2} (NO_{3})_{2}, Mg (NO_{3})_{2} are electrolysed using inert electrodes. Given: E^{0} Ag+/Ag = 0.80 V, E^{0}_{Hg_{2}^{2 +} / Hg} 0.79 V, E^{0}_{Cu^{2 +} / Cu} = 0.24 V and E^{0}_{Mg^{2 +} / Mg} = - 2.37 V . Statement (I): With increasing voltage, the sequence of deposition of metals on the cathode will be Ag, Hg and Cu. Statement (II): Magnesium will not be deposited at the cathode instead oxygen gas will be evolved at the cathode. In the light of the above statements, choose the most appropriate answer from the options given below:$ (1) $Both Statement I and Statement II are incorrect$ (2) $Statement I is incorrect but Statement II is correct$ (3) $Statement I is correct but Statement II is incorrect$ (4) $Both Statement I and Statement II are correct$ 254. $E_{1}, E_{2} and E_{3} are the emfs of the following three galvanic cells respectively. (i) Zn_{(s)} (Zn^{2 +} (0.1 M)) (Cu^{2 +} (1 M)) Cu_{(s)} (ii) Zn_{(s)} (Zn^{2 +} (1 M)) (Cu^{2 +} (1 M)) Cu_{(s)} (iii) Zn_{(s)} (Zn^{2 +} (1 M) ∥ Cu^{2 +} (0.1 M)) Cu_{(s)} Which one of the following is true?$ (1) $E_{2} > E_{1} > E_{3}$ (2) $E_{1} > E_{2} > E_{3}$ (3) $E_{3} > E_{1} > E_{2}$ (4) $E_{3} > E_{2} > E_{1}$ 255. $Standard electrode potential data are useful for understanding the suitability of an oxidant in a redox titration. Some half cell reactions and their standard potentials are given below : MnO_{4}^{-} (aq.) + 8 H^{+} (aq.) + 5 e^{-} \to M n^{2 +} (aq.) + 4 H_{2} O(λ) Eº = 1.51 V C r_{2} O_{7}^{2-} (aq.) + 14 H^{+} (aq.) + 6 e^{-} \to 2 C r^{3 +} (aq.) + 7 H_{2} O(λ) Eº = 1.38 V F e^{3 +} (aq.) + e^{-} \to F e^{2 +} (aq.) Eº = 0.77 V C l_{2} (g) + 2 e^{-} \to 2 C l^{-} (aq.) Eº = 1.40 V Identify the only incorrect statement regarding the quantitative estimation of aqueous Fe (N O_{3})_{2} :$ (1) $MnO_{4}^{-} can be used in aqueous HCl.$ (2) $C r_{2} O_{7}^{2-} can be used in aqueous HCl.$ (3) $MnO_{4}^{-} can be used in aqueous H_{2} S O_{4}$ (4) $C r_{2} O_{7}^{2-} can be used in aqueous H_{2} S O_{4}$ 256. $The unit of conductivity is$ (1) $S / m$ (2) $S / m^{2}$ (3) $Sm$ (4) $none of these.$ 257. $In the cell Pt (s) (H_{2} (g, 1 bar) / HCl (aq) ∥ AgCl (s) / Ag (s)) Pt (s) the cell potential is 0.92 V when a 10^{- 6} molal HCl solution is used. The standard electrode potential of (AgCl / Ag, Cl^{-}) electrode is: (Given : \frac{2.303 RT}{F} = 0.06 V at 298 K)$ (1) $0.94 V$ (2) $0.76 V$ (3) $0.40 V$ (4) $0.20 V$ 258. $The electrode potentials for C u_{(a q)}^{2 +} + e^{-} \to C u_{(a q)}^{+} and C u_{(a q)}^{+} + e^{-} \to C u_{(s)} are + 0.15 V and + 0.50 V respectively. The value of E_{C u^{2 +} / C u}^{\circ} will be$ (1) $0.500 V$ (2) $0.325 V$ (3) $0.650 V$ (4) $0.150 V$ 259. $Galvanization is applying a coating of :$ (1) $Cr$ (2) $Cu$ (3) $Zn$ (4) $Pb$ 260. $Which from following is not true about voltaic cell?$ (1) $The anode acts as negative electrode.$ (2) $The cathode acts as a positive electrode.$ (3) $It converts electrical energy into chemical energy.$ (4) $Dry cell is an example of voltaic cell$ 261. $Which of the following statements is not correct about rusting of iron?$ (1) $Coating of iron surface by tin prevents rusting, even if the tin coating is peeling off.$ (2) $When pH lies above 9 or 10 , rusting of iron does not take place.$ (3) $Dissolved acidic oxides SO_{2}, NO_{2} in water act as catalyst in the process of rusting.$ (4) $Rusting of iron is envisaged as setting up of electrochemical cell on the surface of iron object.$ 262. $Fuel cell, using hydrogen and oxygen as fuels, A. has been used in spaceship B. has as efficiency of 40 % to produce electricity C. uses aluminum as catalysts D. is eco-friendry E. is actually a type of Galvanic cell only Choose the correct answer from the options given below:$ (1) $A, B, D, E only$ (2) $A, D, E only$ (3) $A, B, D only$ (4) $A, B, C only$ 263. $A variable, opposite external potential (E_{e x t}) is applied to the cell Zn\| Zn^{2 +} (1 M) \|\| Cu^{2 +} (1M) \| Cu, of potential 1.1 V. When Eext < 1.1 V and Eext > 1.1 V respectively electrons flow from:$ (1) $Cathode to anode in both cases$ (2) $cathode to anode and anode to cathode$ (3) $anode to cathode and cathode to anode$ (4) $anode to cathode in both cases$ 264. $For the given cell Fe^{2 +}_{(aq)} + Ag^{+}_{(aq)} \to Fe_{(aq)}^{3 +} + Ag_{(s)} The standard cell potential of the above reaction is Ag^{+} + e^{-} \to Ag E^{θ} = xV Given: Fe^{2 +} + 2 e^{-} \to Fe E^{θ} = yV Fe^{3 +} + 3 e^{-} \to Fe E^{θ} = zV$ (1) $x + y - z$ (2) $x + 2 y$ (3) $x + 2 y - 3 z$ (4) $y - 2 x$ 265. $Which of the following is incorrect in a galvanic cell?$ (1) $Oxidation occurs at anode.$ (2) $Reduction occurs at cathode.$ (3) $The electrode at which electrons are gained is called cathode.$ (4) $The electrode at which electrons are lost is called cathode.$ 266. $Consider the following reduction processes: Zn^{2 +} + 2e- \to Zn(s) ; E0 = -0.76 V Ca^{2 +} + 2e- \to Ca(s) ; E0 = -2.86 V Mg^{2 +} + 2e- \to Mg(s) ; E0 = -2.36 V Ni^{2 +} + 2e- \to Ni(s); E0 = -0.25 V The reducing power of the metals increases in the order$ (1) $Ca < Mg < Zn < Ni$ (2) $Ni < Zn < Mg < Ca$ (3) $Ca < Zn < Mg < Ni$ (4) $Zn < Mg < Ni < Ca$ 267. $The electrode potential of M^{2 +} /M of 3d- series elements shows positive value for:$ (1) $Zn$ (2) $Co$ (3) $Fe$ (4) $Cu$ 268. $A hydrogen gas electrode is made by dipping platinum wire in a solution of HCl of p H = 10 and by-passing hydrogen gas around the platinum wire at one atm pressure. The oxidation potential of electrode would be$ (1) $0.118 V$ (2) $1.18 V$ (3) $0.059 V$ (4) $0.59 V$ 269. $The molar conductivity for electrolytes A and B are plotted against C^{1/2} as shown below. Electrolytes A and B respectively are :$ (1) $A: strong electrolyte ; B : weak electrolyte$ (2) $A: weak electrolyte ; B: weak electrolyte$ (3) $A: weak electrolyte ; B: strong electrolyte$ (4) $A: strong electrolyte ; B: strong electrolyte$ 270. $The weight of silver (at. wt. = 108) displaced by a quantity of electricity which displaces 5600 m L of O_{2} at STP will be$ (1) $5.4 g$ (2) $10.8 g$ (3) $54.0 g$ (4) $108.0 g$