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Electrochemistry · Question 18

NEET (UG) 2021MCQMedium📈 Topic in 25% papers+4−1
1

The molar conductivity of 0.007 M acetic acid is 20 S cm2 mol-1. What is the dissociation constant of acetic acid? Choose the correct option. [ H+ = 350 S cm2 mol-1 CH3COO- = 50 S cm2 mol-1]

  1. 2.50 10-5 mol L-1
  2. 1.75 10-4 mol L-1
  3. 2.50 10-4 mol L-1
  4. 1.75 10-5 mol L-1

Answer

(4) 1.75 10-5 mol L-1

Solution

By Kohlrausch's law:

m(CH3COOH) = H+ + CH3COO-

= 350 + 50 = 400 S cm2 mol-1

Degree of dissociation:

= m m = 20400 = 0.05

As per NCERT, Ka = c 21- c 2 (α is small)

⇒ Ka = 0.007 (0.05)2

= 0.007 2.5 10-3

= 1.75 10-5 mol L-1

Answer: (4)

NEET (UG) 2021

Keep practising — Electrochemistry

2

On electrolysis of dil. sulphuric acid using Platinum (Pt) electrode, the product obtained at anode will be :

  1. Oxygen gas
  2. H2S gas
  3. SO2 gas
  4. Hydrogen gas
NEET (UG) 2020
3

The number of Faradays(F) required to produce 20 g of calcium from molten CaCl2 (Atomic mass of Ca = 40 g mol-1) is :

  1. 2
  2. 3
  3. 4
  4. 1
NEET (UG) 2020
4

For a cell involving one electron E cell = 0.59 V at 298 K, the equilibrium constant for the cell reaction is : [Given that 2.303 RTF = 0.059 V at T = 298 K]

  1. 1.0 1030
  2. 1.0 1010
  3. 1.0 102
  4. 1.0 105
NEET (UG) 2019
5

For the cell reaction 2Fe3+(aq) + 2I-(aq) 2Fe2+(aq) + I2(aq) E cell = 0.24 V at 298 K. The standard Gibbs energy ( r G ) of the cell reaction is : [Given that Faraday constant F = 96500 C mol-1]

  1. 46.32 kJ mol-1
  2. 23.16 kJ mol-1
  3. -46.32 kJ mol-1
  4. -23.16 kJ mol-1
NEET (UG) 2019
6

In the electrochemical cell : Zn | ZnSO4 (0.01 M) || CuSO4 (1.0 M) | Cu, the emf of this Daniell cell is E1. When the concentration of ZnSO4 is changed to 1.0 M and that of CuSO4 changed to 0.01 M, the emf changes to E2. From the following, which one is the relationship between E1 and E2? (Given, 2.303RTF = 0.059)

  1. E1 < E2
  2. E1 > E2
  3. E2 = 0 E1
  4. E1 = E2
NEET 2017
7

The pressure of H2 required to make the potential of H2-electrode zero in pure water at 298 K is

  1. 10-10 atm
  2. 10-4 atm
  3. 10-14 atm
  4. 10-12 atm
NEET 2016 (Phase 1)
8

The molar conductivity of a 0.5 mol/dm3 solution of AgNO3 with electrolytic conductivity of 5.76 10-3 S cm-1 at 298 K is

  1. 2.88 S cm2/mol
  2. 11.52 S cm2/mol
  3. 0.086 S cm2/mol
  4. 28.8 S cm2/mol
NEET 2016 (Phase 2)
9

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

  1. 55 minutes
  2. 110 minutes
  3. 220 minutes
  4. 330 minutes
NEET 2016 (Phase 2)
10

If the E cell for a given reaction has a negative value, which of the following gives the correct relationships for the values of G and Keq ?

  1. G > 0; Keq < 1
  2. G > 0; Keq > 1
  3. G < 0; Keq > 1
  4. G < 0; Keq < 1
NEET 2016 (Phase 2)
11

The number of electrons delivered at the cathode during electrolysis by a current of 1 ampere in 60 seconds is (charge on electron = 1.60 10-19 C)

  1. 6 1023
  2. 6 1020
  3. 3.75 1020
  4. 7.48 1023
NEET 2016 (Phase 2)

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