12th Standard Chemistry Electro Chemistry English Medium Free Online Test One Mark Questions with Answer Key 2020 - 2021

12th Standard

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Chemistry

Time : 00:20:00 Hrs
Total Marks : 20
20 x 1 = 20
1. Consider the following half cell reactions.
Mn2+ + 2e− ➝ Mn Eo = -1.18V
Mn2+ ➝Mn3+ e- Eo = -1.51V
The Eo for the reaction 3Mn2+ ➝ Mn+2Mn3+ , and the possibility of the forward reaction are respectively

(a)

2.69V and spontaneous

(b)

-2.69 and non spontaneous

(c)

0.33V and Spontaneous

(d)

4.18V and non spontaneous

2. Faradays constant is defined as

(a)

charge carried by 1 electron

(b)

charge carried by one mole of electrons

(c)

charge required to deposit one mole of substance

(d)

charge carried by 6.22 ×1010 electrons

3. The number of electrons delivered at the cathode during electrolysis by a current of 1A in 60 seconds is (charge of electron = 1.6 ×10−19C )

(a)

6.22 ×1023

(b)

6.022 ×1020

(c)

3.75 ×1020

(d)

7.48 ×1023

4. While charging lead storage battery

(a)

PbSO4 on cathode is reduced to Pb

(b)

PbSO4 on anode is oxidised to PbO2

(c)

PbSO4 on anode is reduced to Pb

(d)

PbSO4 on cathode is oxidised to Pb

5. In H2-Ofuel cell the reaction occur at cathode is

(a)

O2(g) + 2H2O (l) + 4e- ⟶ 4OH (aq)

(b)

H+(aq) + OH (aq) ⟶ H2O (l)

(c)

2H2 (g) + O (g) ⟶ 2H2O (g)

(d)

H+ + e-+ ⟶ 1/2 H2

6. In the electrochemical cell: Zn|ZnSO4 (0.01M)|| CuSO4 (1.0M)| Cu, the emf of this Daniel cell is E1. When the concentration of ZnSO4 is changed to 1.0M and that CuSO4 changed to 0.01M, the emf changes to E2. From the followings, which one is the relationship between E1 and E2?

(a)

E1 < E2

(b)

E1 > E2

(c)

E2=0 $\uparrow$E1

(d)

E1=E2

7. A gas X at 1 atm is bubble through a solution containing a mixture of 1MY- and 1MZ- at 25oC . If the reduction potential of Z>Y>X, then

(a)

Y will oxidize X and not Z

(b)

Y will oxidize Z and not X

(c)

Y will oxidize both X and Z

(d)

Y will reduce both X and Z

8. Pick out the correct statement regarding resistance of an electrolytic solution

(a)

It is inversely proportional to the length (I)

(b)

It is inversely proportional to the cross sectional area (A)

(c)

It is directly proportional to the cross sectional area (A)

(d)

Resistivity is denoted by p (rho)

9. Which of the statements about electrolytic conductance is not true?

(a)

Conductivity increases with decrease in viscosity.

(b)

Higher dielectric constant shows lower conductance in solution.

(c)

Temperature increases, conductance also increases.

(d)

Molar conductance increases with increase in dilution.

10. Kohlraush's law is applied to calculate

(a)

molar conductance at infinite dilution of a weak electrolyte

(b)

degree of dissociation of weak electrolyte

(c)

solubility of a sparingly soluble salt

(d)

all the above

11. The laws of electrolysis were enunciated first by

(a)

Dalton

(b)

(c)

Kekule

(d)

12. For the given cell
Cr(s)|Cr3+(aq)||Cu2+(aq)|Cu(s) which is correct?

(a)

Cr is the anode

(b)

Cu is the anode

(c)

Overall cell reaction is 2Cr3+(aq) +3Cu(s) ⟶ 2Cr(s) + 3Cu2+(aq)

(d)

Cu is the anode and Overall cell reaction is 2Cr3+(aq) +3Cu(s) ⟶ 2Cr(s) + 3Cu2+(aq)

13. The standard conditions for determination of standard emf of the cell are

(a)

1M solution of the reactant

(b)

temperature of 25°C

(c)

both 1M solution of the reactant and temperature of 25°C

(d)

none of these

14. The quantity of charge required to obtain 1 mole of aluminum from Al2O3 is _______

(a)

2F

(b)

3F

(c)

6F

(d)

12F

15. Leclanche cell is _________

(a)

primary battery

(b)

secondary battery

(c)

rechargeable

(d)

both secondary battery and rechargeable

16. When a zinc metal strip is placed in a copper sulphate solution the blue colour of the solution fades and copper is deposited on the zinc strip as red - brown crust. The oxidation half cell reaction of the above process is represented as __________

(a)

Cu2+(aq) + 2e- ⟶ Cu(s)

(b)

Cu(s) ⟶ Cu2++ 2e-

(c)

Zn(S) ⟶ Zn2+(aq) + 2e-

(d)

Zn2+(aq) + 2e- ⟶ Zn(s)

17. Debye constants A and B depend on _____________

(a)

nature of the solvent

(b)

temperature

(c)

concentration of the solvent

(d)

both nature of the solvent and temperature

18. _______ is the reciprocal of resistance

(a)

specificconductance

(b)

molar conductance

(c)

specificresistance

(d)

conductance

19. The electrode where there is gain of electrons is called ____________

(a)

cathode

(b)

anode

(c)

electrode

(d)

both anode and electrode

20. SHE is ___________

(a)

Standard Helium Electorde

(b)

Standard Hydrogen Electrode

(c)

Standard Mercury Electrode

(d)

none of these