NEET Chemistry Electrochemistry MCQs Set 03

Question: How many grams of cobalt metal will be deposited when a solution of cobalt(II) chloride is electrolyzed with a current of 10 amperes for 109 minutes (1 Faraday = 96,500 C; Atomic mass of Co = 59 u)

• a) 0.66
• b) 4.0
• c) 20.0
• d) 40.0

Answer: 20.0

Question: A 5 ampere current is passed through a solution of zinc sulphate for 40 minutes. The amount of zinc deposited at the cathode is

• a) 0.4065 gm
• b) 65.04 gm
• c) 40.65 gm
• d) 4.065 gm

Answer: 4.065 gm

Question:  The molar conductances of NaCl, HCl and CH₃COONa at infinite dilution are 126.45, 426.16 and 91 ohm^–1 cm²mol^–1 respectively. The molar conductance of CH₃COOH at infinite dilution is

• a) 698.28 ohm^–1 cm² mol^–1
• b) 540.48 ohm^–1 cm² mol^–1
• c) 201.28 ohm^–1 cm² mol^–1 
• d) 390.71 ohm^–1 cm² mol^–1

Answer:  390.71 ohm^–1 cm² mol^–1

Question:  E° for the cell, Zn|Zn²⁺(aq)||Cu²⁺(aq)|Cu is 1.10 V at 25ºC, the equilibrium constant for the reaction

is the order of

• a) 10⁺¹⁸
• b) 10⁺³⁷
• c) 10^–28
• d) 10^–37

Answer:  10⁺³⁷

Question:  For the cell reaction, Cu²⁺ (C₁· aq) + Zn(s) = Zn²⁺ (C₂· aq) + Cu(s) of an electrochemical cell, the change in Free Energy ΔG at a given temperature is a function of

• a) ln (C₂) 
• b) ln (C₂/C₁)
• c) ln (C₁) 
• d) ln (C₁+ C₂)

Answer:  ln (C₂/C₁)

Question:  The specific conductance of a 0.1 N KCl solution at 23°C is 0.012 ohm^–1 cm^–1. The resistance of cell containing the solution at the same temperature was found to be 55 ohm. The cell constant will be

• a) 0.918 cm^–1
• b) 0.66 cm^–1
• c) 1.142 cm^–1 
• d) 1.12 cm^–1

Answer:  0.66 cm^–1

Question:  For the disproportionation of copper 2Cu⁺ → Cu²⁺ Cu, E° is (Given E° for Cu²⁺/Cu is 0.34 V and E° for Cu²⁺/Cu⁺ is 0.15 V)

• a) 0.49 V
• b) –0.19 V
• c) 0.38 V
• d) –0.38 V

Answer: 0.38 V

Question: Cell reaction is spontaneous when

• a) ΔG° is negative 
• b) ΔG° is positive
• c) ΔE°_Red is positive
• d) ΔE°_Red is negative

Answer:  ΔG° is negative 

Question:  Equivalent conductances of Ba²⁺ and Cl^– ions are 127 and 76 ohm^–1 cm^–1 eq^–1 respectively. Equivalent conductance of BaCl₂ at infinite dilution is (in the unit ohm^–1 cm^–1 eq^–1)

• a) 139.5
• b) 101.5
• c) 203
• d) 279

Answer: 203

Question:  Standard electrode potentials are

Fe²⁺/Fe ; E° = –0.44 volts

Fe³⁺/Fe²⁺ ; E° = 0.77 volts

Fe²⁺, Fe³⁺ and Fe blocks are kept together, then

• a) Fe³⁺ increases
• b) Fe³⁺ decreases
• c) Fe²⁺/Fe³⁺ remains unchanged
• d) Fe²⁺ decreases

Answer:  Fe³⁺ decreases

More Questions.................................

Question:

PbO₂→ PbO     ΔG₂₉₈< 0

SnO₂→ SnO    ΔG₂₉₈> 0

Most probable oxidation state of Pb and Sn will be

• a) Pb⁴⁺, Sn⁴⁺ 
• b) Pb⁴⁺, Sn²⁺
• c) Pb²⁺, Sn²⁺ 
• d) Pb²⁺, Sn⁴⁺

Answer:  Pb²⁺, Sn⁴⁺

Question: The most convenient method to protect the bottom of ship made of iron is

• a) Coating it with red lead oxide
• b) White tin plating
• c) Connecting it with Mg block
• d) Connecting it with Pb block

Answer: White tin plating

Question:  In electrolysis of NaCl when Pt electrode is taken then H₂ is liberated at cathode while with Hg cathode it forms sodium amalgam

• a) Hg is more inert than Pt
• b) More voltage is required to reduce H⁺ at Hg than at Pt
• c) Na is dissolved in Hg while it does not dissolve in Pt
• d) Conc. of H⁺ ions is larger when Pt electrode is taken

Answer:  More voltage is required to reduce H⁺ at Hg than at Pt

Question:  On the basis of the information available from the reaction of O₂, 

the minimum e.m.f. required to carry out electrolysis of Al₂O₃ is (F = 96500 C mol^–1)

• a) 2.14 V
• b) 4.28 V
• c) 6.42 V
• d) 8.56

Answer: 2.14 V

Question:  The e.m.f. of a Daniel cell at 298 K is E₁

When the concentration of ZnSO₄ is 1.0 M and that of CuSO₄ is 0.01 M, the e.m.f. changed to E₂. What is therelationship between E₁and E₂?

• a) E₁> E₂
• b) E₁< E₂  
• c) E₁= E₂ 
• d) E₂= 0 ≠ E₁

Answer:  E₁> E₂

Question:  The standard e.m.f. of a galvanic cell involving cell reaction with n = 2 is found to be 0.295 V at 25°C. The equilibrium constant of the reaction would be (Given F = 96500 C mol^–1, R = 8.314 J K^–1 mol^–1)

• a) 2.0 × 10¹¹
• b) 4.0 × 10¹²
• c) 1.0 × 10²
• d) 1.0 × 10¹⁰

Answer: 1.0 × 10¹⁰

Question: The mass of carbon anode consumed (giving only carbon dioxide) in the production of 270 kg of aluminium metal from bauxite by the Hall process is (Atomic Mass: Al = 27)

• a) 270 kg
• b) 540 kg
• c) 90 kg
• d) 180 kg

Answer: 90 kg

Question:  Consider the half-cell reduction reaction :

Mn²⁺ + 2e^– → Mn, E^o = –1.18 V

Mn²⁺ →  Mn³⁺ + e^–, E^o = –1.51 V

The E^o for the reaction 3 Mn²⁺→  Mn⁰ + 2 Mn³⁺, and possibility of the forward reaction are, respectively

• a) –2.69 V and no
• b) –4.18 V and yes
• c) +0.33 V and yes
• d) +2.69 V and no

Answer: –2.69 V and no

Question: Aqueous solution of which of the following compounds is the best conductor of electric current?

• a) Ammonia, NH₃ 
• b) Fructose, C₆H₁₂O₆
• c) Acetic acid, C₂H₄O₂ 
• d) Hydrochloric acid, HCl

Answer: Hydrochloric acid, HCl

Question: A device that converts energy of combustion of fuels like hydrogen and methane, directly into electrical energy is known as

• a) Ni-Cd cell
• b) Fuel cell
• c) Electrolytic cell
• d) Dynamo

Answer: Fuel cell

Question:  A current of 0.965 ampere is passed through 500 ml of 0.2 M solution of ZnSO₄ for 10 minutes. The molarity of Zn²⁺ after deposition of zinc is

• a) 0.1 M
• b) 0.5 M
• c) 0.8 M
• d) 0.194 M

Answer: 0.194 M

Question:  The hydrogen electrode is dipped in a solution of pH = 3 at 25°C. The reduction potential of the electrode would be

• a) 0.177 V
• b) 0.087 V
• c) –0.177 V
• d) 0.059 V

Answer: –0.177 V

Question:   The two platinum electrodes filted in a conductance cell are 1.5 cm apart while the cross sectional area of each electrode is 0.75 cm². What is the cell constant?

• a) 1.25 cm
• b) 0.5 cm
• c) 2.0 cm^–1
• d) 0.2 cm^–1

Answer:  2.0 cm^–1

Question:  A 100 watt, 110 volt lamp is connected in series with an electrolytic cell containing CdSO₄ solution, the weight of Cd deposited by the current for 10 hrs is (At. wt. Cd = 112.4)

• a) 19.06 g
• b) 38.12 g
• c) 1.906 g
• d) 3.812 g

Answer: 19.06 g

Question: The quantity of electricity required to reduce 12.3 g of nitro benzene to aniline assuming 50% current effeciency is

• a) 115800 C
• b) 57900 C
• c) 231600 C
• d) 28950 C

Answer: 115800 C

Question:   Electrolysis of H₂SO₄(conc.) gives the following at anode

• a) H₂
• b) O₂
• c) H₂S₂O₃
• d) H₂S₂O₈

Answer:  H₂S₂O₈

Question: In SHE, the pH of the acid solution should be

• a) 7
• b) 14
• c) 0
• d) 4

Answer: 0

Question: Which of the following can oxidise fluoride ions?

• a) O₃ 
• b) Cl₂
• c) Br₂ 
• d) No chemical substance

Answer: No chemical substance

Question:  2.5 faraday of electricity is passes through a solution of CuSO₄ . The number of gram eqivalents of copper deposited on the cathode will be

• a) 1
• b) 2
• c) 2.5
• d) 1.25

Answer: 2.5

Question: The coulombic charge on one mole electron is

• a) 1.6 × 10^–19 C
• b) 96500 C
• c) 6.02 × 10^–23 C
• d) 1.6 × 10^–23 C

Answer: 96500 C