Free NEET Chemistry multiple-choice questions on Electrolysis & Batteries. Attempt each question and reveal the answer with a full explanation.
When electricity is passed through water acidified with H 2SO 4 , the volumes of H 2 and O 2 liberated at STP are in the ratio: 2:1 1:1 1:2 8:1 In the electrolysis of aqueous AgNO 3 solution using silver electrodes: Silver dissolves at the anode and is deposited at the cathode Oxygen is evolved at the anode Hydrogen is evolved at the cathode Silver is deposited at the anode The amount of charge required to produce 20 g of calcium from molten CaCl 2 is: (Atomic mass of Ca = 40 g/mol ) 1 F 2 F 0.5 F 4 F Which of the following statements is true for the electrolysis of molten PbBr 2 ? Bromine gas is evolved at the anode Lead is deposited at the anode Hydrogen gas is evolved at the cathode Bromine gas is evolved at the cathode The device that converts energy of combustion of fuels like hydrogen and methane directly into electrical energy is known as: Fuel cell Electrolytic cell Dynamo Ni-Cd cell Which of the following is used to coat the glass in the construction of a silver-zinc button cell? Ag 2O ZnO AgCl ZnCl 2 In the Mercury cell, the cathode is made of: A paste of HgO and carbon Zinc-Mercury amalgam Carbon rod Lead dioxide The cathode of a typical dry cell (Leclanché cell) consists of: A graphite rod surrounded by MnO 2 and carbon A zinc container A lead plate coated with PbO 2 A nickel plate The number of Faraday's required to produce 2.0 mol of O 2 from water is: 8 4 2 1 Which type of electrochemical cell is a Nickel-Cadmium (Ni-Cd) cell? Secondary cell Primary cell Fuel cell Concentration cell 4.5g of aluminium (at. mass 27 amu) is deposited at cathode from Al 3+ solution by a certain quantity of electric charge. The volume of hydrogen produced at STP from H + ions in solution by the same quantity of electric charge will be - 44.8L 11.2L 22.4L 5.6L In a Leclanché cell (dry cell), the substance that acts as a depolarizer to prevent the accumulation of hydrogen gas is: MnO 2 NH 4Cl ZnCl 2 Graphite In producing chlorine through electrolysis 100 watt power at 125V is being consumed. How much chlorine per minute is liberated ? E.C.E. of chlorine is 0.367 10 -6 kg/coulomb :- 17.6 mg 21.3 mg 24.3 mg 13.6 mg The efficiency of a fuel cell is given by G/ S G/ H S/ G H/ G On electrolysis of dil. sulphuric acid using Platinum (Pt) electrode, the product obtained at anode will be Oxygen gas H2S gas SO2 gas Hydrogen gas Mass in grams of copper deposited by passing 9.6487 A current through a voltmeter containing copper sulphate solution for 100 seconds is (Given : Molar mass of Cu : 63 g mol -1 , 1 F = 96487 C) 3.15 g 0.315 g 31.5 g 0.0315 g In a lead-acid battery, during discharging: H 2SO 4 is consumed PbSO 4 is consumed PbO 2 is formed H 2SO 4 is formed What is the product formed at the anode during the electrolysis of aqueous Na 2SO 4 using inert electrodes? O 2 H 2 SO 2 Na During the electrolysis of aqueous sodium chloride (brine), the pH of the solution: Increases Decreases Remains constant Initially decreases and then increases In the electrolysis of aqueous CuSO 4 using copper electrodes, which of the following occurs? Copper dissolves at the anode and deposits at the cathode Oxygen gas is evolved at the anode Hydrogen gas is evolved at the cathode The concentration of Cu 2+ in the solution decreases When electricity is passed through a solution of AlCl 3 , 13.5 g of Al (at. wt. = 27) is deposited. The number of Faradays of electricity passed is: 1.5 0.5 1.0 3.0 During the electrolysis of dilute sulphuric acid using platinum electrodes, the product obtained at the anode is: O 2 gas H 2 gas SO 2 gas SO 4 2- ions The Faraday constant ( F ) is numerically equal to: The product of the charge of an electron and the Avogadro constant The charge of one gram of ions The charge of one mole of any substance The ratio of the Avogadro constant to the charge of an electron If the same quantity of electricity is passed through solutions of AgNO 3 and CuSO 4 connected in series, and 1.08 g of Ag is deposited, the mass of Cu deposited will be (At. wt. Ag=108, Cu=63.5 ): 0.3175 g 0.635 g 1.27 g 2.16 g During the charging of a lead-acid storage battery: PbSO 4 on the anode is reduced to Pb PbSO 4 on the cathode is reduced to Pb Pb is converted to PbSO 4 Sulphuric acid is consumed During the electrolysis of aqueous CuSO 4 using platinum electrodes, the solution around the cathode becomes: Neutral Acidic Basic Colorless How many moles of Pt may be deposited on the cathode when 0.80 F of electricity is passed through a solution of PtCl 4 ? 0.20 0.40 0.10 0.80 During the electrolysis of aqueous AgNO 3 using platinum (inert) electrodes, the product(s) obtained at the anode and cathode are, respectively: O 2 and Ag Ag and O 2 NO 2 and Ag O 2 and H 2 When 0.1 Faraday of electricity is passed through a solution of CuSO 4 , the mass of copper deposited on the cathode is (At. wt. of Cu = 63.5 ): 3.175 g 6.35 g 12.7 g 31.75 g The quantity of electricity (in Coulombs) required to deposit 4.5 g of Aluminium (atomic mass 27 u ) from a molten Al 3O 3 bath is: 48250 C 96500 C 144750 C 24125 C Calculate the mass of magnesium deposited by a current of 2 A passing through molten MgCl 2 for 30 minutes. (Atomic mass of Mg = 24 ): 0.447 g 0.895 g 1.200 g 2.400 g In the electrolysis of aqueous CuSO 4 using platinum (inert) electrodes, the pH of the solution: Decreases Increases Remains constant First increases then decreases The efficiency of a fuel cell is typically higher than a conventional thermal power plant because: It converts chemical energy directly into electrical energy without a heat engine It operates at extremely high pressures It uses platinum as a catalyst It does not involve any redox reactions In a Nickel-Cadmium (Ni-Cd) rechargeable cell, the anode is made of: Cadmium metal Nickel hydroxide Nickel dioxide Lead In the electrolysis of aqueous NaCl , the discharge of Cl - at the anode is preferred over OH - due to: Overpotential of oxygen Lower reduction potential of Cl - Higher concentration of Cl - Higher mobility of Cl - During the discharge of a lead-storage battery, the reaction taking place at the anode is: Pb(s) + SO 4 2- (aq) PbSO 4(s) + 2e - PbSO 4(s) + 2e - Pb(s) + SO 4 2- (aq) PbO 2(s) + 4H + + SO 4 2- + 2e - PbSO 4(s) + 2H 2O Pb 2+ + 2e - Pb(s) A current of 2.0 A is passed for 5 hours through a molten tin salt to deposit 22.2 g of tin (At. wt. = 118.7 ). What is the oxidation state of tin in the salt? +2 +1 +3 +4 During the electrolysis of brine ( NaCl solution), why is a mercury cathode used in the Castner-Kellner cell? To produce sodium amalgam and prevent reaction with water To increase the rate of chlorine evolution Because mercury is a better conductor than iron To lower the melting point of the electrolyte How many Coulombs of electricity are required to reduce 500 mL of 0.1 M CuSO 4 solution to copper metal? 9650 C 19300 C 4825 C 96500 C Porous electrodes coated with catalytic materials (like Pt or Pd) are used in fuel cells primarily to: Increase the surface area and provide a site for gas-electrolyte-electrode contact Act as a filter to purify the gases Prevent the cell from overheating Decrease the internal resistance by being highly conductive In a lead-acid battery, the density of the electrolyte ( H 2SO 4 ) decreases during discharge because: Sulfuric acid is consumed and water is produced Lead is converted to lead oxide Water is evaporated due to heat Sulfuric acid reacts with the plastic casing Which of the following describes the change in the electrolyte during the charging of a lead-acid storage battery? Sulfuric acid is regenerated and its density increases. Lead sulfate is consumed and water is produced. Sulfuric acid is consumed and its density decreases. Lead dioxide is converted into lead sulfate. During the electrolysis of an aqueous solution of Sodium Iodide ( NaI ) using inert electrodes, what is produced at the anode? I 2(s) O 2(g) Na(s) H 2(g) A current of 9.65 A is passed for 1000 seconds through a solution of CuSO 4 . The number of moles of Copper deposited is: 0.05 0.10 0.01 0.50 The number of moles of electrons required to deposit 1 g equivalent of any substance is: 1 2 3 0.5 The thermodynamic efficiency of a fuel cell is given by the ratio: G / H G / S H / G T S / G In modern lithium-ion batteries used in smartphones, the anode is typically made of: Lithium-intercalated graphite Pure lithium metal Lithium cobalt oxide Manganese dioxide The mass of carbon anode consumed (giving only carbondioxide) in the production of 270 kg of aluminium metal from bauxite by the Hall process is :- (Atomic mass : Al = 27) 90 kg 540 kg 180 kg 270 kg Al 2O 3 is reduced by electrolysis at low potentials and high currents. If 4.0 10 4 amperes of current is passed through molten Al 2O 3 for 6 hours, what mass of aluminium is produced ? (Assume 100% current efficiency, at. mass of Al = 27 g mol -1 ) - 1.3 10 4 g 9.0 10 3 g 8.1 10 4 g 2.4 10 5 g When 0.1 mol MnO4 2- is oxidised the quantity of electricity required to completely oxidise MnO4 2- to MnO4 - is :- 96500 C 2 96500 C 9650 C 96.50 C The weight of silver (at wt. = 108) displaced by a quantity of electricity which displaces 5600 mL of O2 at STP will be :- 5.4 g 10.8 g 54.9 g 108.0 g The number of Faradays(F) required to produce 20 g of calcium from molten CaCl2 , (Atomic mass of Ca = 40 g mol -1 ) is 2 3 4 1 Match List I with List II. array ll List I (Conversion) & List II (Number of Faraday required) A. 1 mol of H2O to O2 & I. 3F B. 1 mol of MnO4 - to Mn 2+ & II. 2F C. 1.5 mol of Ca from molten CaCl2 & III. 1F D. 1 mol of FeO to Fe2O3 & IV. 5F array Choose the correct answer from the options given below: A-II, B-IV, C-I, D-III A-III, B-IV, C-I, D-II A-II, B-III, C-I, D-IV A-III, B-IV, C-II, D-I A solution of copper sulphate is electrolysed for 10 minutes with a current of 1.5 amperes. The mass of copper deposited at cathode is : (Given : Molar mass of Cu = 63 g mol -1 ; 1 F = 96487 C mol -1 ) 0.2938 g 0.5876 g 2.4036 g 1.7018 g During the electrolysis of molten sodium chloride, the time required to produce 0.10 mol of chlorine gas using a current of 3 Amperes is: 107.2 min 53.6 min 214.4 min 6.6 min In the Mercury cell, which is used in low current devices like hearing aids, the electrolyte consists of a paste of: KOH and ZnO NH 4Cl and ZnCl 2 LiOH and Ni(OH) 2 H 2SO 4 and PbSO 4 The weight of silver (at. wt. = 108) displaced by a quantity of electricity which displaces 5600 mL of O 2 at STP will be: 108.0 g 5.4 g 10.8 g 54.0 g A Daniell cell is connected to an external voltage source E ext . If E ext > 1.1 V (where 1.1 V is the E cell ), then: Electrons flow from Cu to Zn and Zn is deposited at the Zn electrode Electrons flow from Zn to Cu and Cu is deposited at the Cu electrode No current flows The cell potential becomes zero Which of the following is the reaction at the anode during the charging of a Lead-acid storage battery? PbSO 4(s) + 2H 2O(l) PbO 2(s) + SO 4 2- (aq) + 4H +(aq) + 2e - PbSO 4(s) + 2e - Pb(s) + SO 4 2- (aq) Pb(s) + SO 4 2- (aq) PbSO 4(s) + 2e - PbO 2(s) + SO 4 2- (aq) + 4H + + 2e - PbSO 4(s) + 2H 2O During the charging of a nickel-cadmium (Ni-Cd) cell, which of the following processes occurs? Ni(OH) 2 is oxidized to NiO(OH) Cd is oxidized to Cd(OH) 2 NiO(OH) is reduced to Ni(OH) 2 Cd(OH) 2 is oxidized to Cd 2+ If the same quantity of electricity is passed through molten AlCl 3 , MgCl 2 , and NaCl , the ratio of the number of moles of Al , Mg , and Na deposited at the cathodes will be: 2 : 3 : 6 1 : 2 : 3 3 : 2 : 1 6 : 3 : 2 During the electrolysis of aqueous H 2SO 4 with high current density, the product formed at the anode is: H 2S 2O 8 O 2 SO 2 H 2O 2 During the Kolbe's electrolysis of an aqueous solution of sodium acetate ( CH 3COONa ), the gases evolved at the anode are: Ethane and Carbon dioxide Methane and Oxygen Hydrogen and Carbon dioxide Ethane and Hydrogen A secondary cell is one which: Can be recharged by passing current in the opposite direction Can be used only once and then becomes dead Has its chemical energy converted into electrical energy irreversibly Generates electricity through combustion of fuels The protection of iron by coating it with a layer of zinc is called: Galvanization Electropolishing Annealing Cathodic induction Which of the following statements is true for a Nickel-Cadmium (Ni-Cd) cell? It is a secondary cell and has a longer life than lead-acid batteries It is a primary cell and cannot be recharged The overall reaction involves the evolution of hydrogen gas It uses concentrated sulphuric acid as an electrolyte