Electrochemistry

Several blocks of magnesium are fixed to the bottom of a ship to :

In a hydrogen – oxygen fuel cell, combustion of hydrogen occurs to :

In a fuel cell methanol is used as fuel and oxygen gas is used as an oxidizer. The reaction is CH₃OH(l) + 3/2O_2 $$\to$$ CO₂ (g) + 2H₂O (l) At 298K standard Gibb’s energies of formation for CH₃OH(l), H₂O(l) and CO₂ (g) are -166.2, -237.2 and -394.4 kJ mol^−1 respectively. If standard enthalpy of combustion of methanol is -726 kJ mol^−1, efficiency of the fuel cell will be

Galvanization is applying a coating of :

Identify the correct statement :

Compound A used as a strong oxidizing agent is amphoteric in nature. It is the part of lead storage batteries. Compound A is :

Match List - I with List - II. .tg {border-collapse:collapse;border-spacing:0;} .tg td{border-color:black;border-style:solid;border-width:1px;font-family:Arial, sans-serif;font-size:14px; overflow:hidden;padding:10px 5px;word-break:normal;} .tg th{border-color:black;border-style:solid;border-width:1px;font-family:Arial, sans-serif;font-size:14px; font-weight:normal;overflow:hidden;padding:10px 5px;word-break:normal;} .tg .tg-c3ow{border-color:inherit;text-align:center;vertical-align:top} .tg .tg-7btt{border-color:inherit;font-weight:bold;text-align:center;vertical-align:top} .tg .tg-fymr{border-color:inherit;font-weight:bold;text-align:left;vertical-align:top} .tg .tg-0pky{border-color:inherit;text-align:left;vertical-align:top} List - I List - II (A) $$Cd(s) + 2Ni{(OH)_3}(s) \to CdO(s) + 2Ni{(OH)_2}(s) + {H_2}O(l)$$ (I) Primary battery (B) $$Zn(Hg) + HgO(s) \to ZnO(s) + Hg(l)$$ (II) Discharging of secondary battery (C) $$2PbS{O_4}(s) + 2{H_2}O(l) \to Pb(s) + Pb{O_2}(s) + 2{H_2}S{O_4}(aq)$$ (III) Fuel cell (D) $$2{H_2}(g) + {O_2}(g) \to 2{H_2}O(l)$$ (IV) Charging of secondary battery Choose the correct answer from the options given below:

The molar conductivities $$\wedge _{NaOAc}^o$$ and $$\wedge _{HCl}^o$$ and at infinite dilution in water at 25^oC are 91.0 and 426.2 Scm²/mol respectively. To calculate $$\wedge _{HOAc}^o$$ , the additional value required is

For lead storage battery pick the correct statements A. During charging of battery, $$\mathrm{PbSO}_{4}$$ on anode is converted into $$\mathrm{PbO}_{2}$$ B. During charging of battery, $$\mathrm{PbSO}_{4}$$ on cathode is converted into $$\mathrm{PbO}_{2}$$ C. Lead storage battery consists of grid of lead packed with $$\mathrm{PbO}_{2}$$ as anode D. Lead storage battery has $$\sim 38 \%$$ solution of sulphuric acid as an electrolyte Choose the correct answer from the options given below:

Which of the following statements is not correct about rusting of iron?

Match List I with List II .tg {border-collapse:collapse;border-spacing:0;} .tg td{border-color:black;border-style:solid;border-width:1px;font-family:Arial, sans-serif;font-size:14px; overflow:hidden;padding:10px 5px;word-break:normal;} .tg th{border-color:black;border-style:solid;border-width:1px;font-family:Arial, sans-serif;font-size:14px; font-weight:normal;overflow:hidden;padding:10px 5px;word-break:normal;} .tg .tg-c3ow{border-color:inherit;text-align:center;vertical-align:top} .tg .tg-7btt{border-color:inherit;font-weight:bold;text-align:center;vertical-align:top} .tg .tg-0pky{border-color:inherit;text-align:left;vertical-align:top} LIST I (Cell) LIST II (Use/Property/Reaction) A. Leclanche cell I. Converts energy of combustion into electrical energy B. Ni - Cd cell II. Does not involve any ion in solution and is used in hearing aids C. Fuel cell III. Rechargeable D. Mercury cell IV. Reaction at anode $$\mathrm{Zn} \rightarrow \mathrm{Zn}^{2+}+2 \mathrm{e}^{-}$$ Choose the correct answer from the options given below :

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-friendly E. is actually a type of Galvanic cell only Choose the correct answer from the options given below:

The reaction at cathode in the cells commonly used in clocks involves.

Conductivity (Seimen’s S) is directly proportional to area of the vessel and the concentration of the solution in it and is inversely proportional to the length of the vessel then, then constant of proportionality is expressed in :

When during electrolysis of a solution of AgNO₃, 9650 coulombs of charge pass through the electroplating bath, the mass of silver deposited on the cathode will be :

The limiting molar conductivities Λ° for NaCl, KBr and KCl are 126, 152 and 150 S cm² mol⁻¹ respectively. The Λ° for NaBr is

Aluminium oxide may be electrolysed at 1000^oC to furnish aluminium metal (Atomic mass = 27 amu; 1 Faraday = 96,500 Coulombs). The cathode reaction is Al³⁺ + 3e⁻ $$\to$$ Al^o To prepare 5.12 kg of aluminium metal by this method would require

The highest electrical conductivity of the following aqueous solutions is of :

.tg {border-collapse:collapse;border-spacing:0;} .tg td{font-family:Arial, sans-serif;font-size:14px;padding:10px 5px;border-style:solid;border-width:1px;overflow:hidden;word-break:normal;border-color:black;} .tg th{font-family:Arial, sans-serif;font-size:14px;font-weight:normal;padding:10px 5px;border-style:solid;border-width:1px;overflow:hidden;word-break:normal;border-color:black;} .tg .tg-c3ow{border-color:inherit;text-align:center;vertical-align:top} .tg .tg-uys7{border-color:inherit;text-align:center} .tg .tg-xldj{border-color:inherit;text-align:left} .tg .tg-0pky{border-color:inherit;text-align:left;vertical-align:top} Electrolyte: KCl KNO₃ HCl NaOAc NaCl $${ \wedge ^\infty }(Sc{m^2}mo{l^{ - 1}}):$$ 149.9 145 426.2 91 126.5 Calculate $$\wedge _{HOAc}^\infty$$ Using appropriate molar conductances of the electrolytes listed above at infinite dilution in H₂O at 25^oC